Answer:
3) 310 g/mol
Explanation:
Hello,
In this case, for calcium carbonate, we are able to compute its gram-formula mass by considering the atomic mass of each element composing it and their subscripts as shown below:
[tex]M=3*m_{Ca}+2*m_P+4*2*m_O\\[/tex]
Thus, we compute:
[tex]M=3*40g/mol+2*31g/mol+4*2*16g/mol\\\\M=310g/mol[/tex]
Hence answer is 3) 310 g/mol . Remember this is also known as the molar mass of the mentioned compound.
Best regards.
A gas company in Massachusetts charges $2.80 for 15.0 ft3 of natural gas (CH4) measured at 20.0°C and 1.00 atm. Calculate the cost of heating 2.00 × 102 mL of water (enough to make a cup of coffee or tea) from 20.0°C to 100.0°C. Assume that only 50.0% of the heat generated by the combustion is used to heat the water; the rest of the heat is lost to the surroundings. Assume that the products of the combustion of methane are CO2(g) and H2O(l).
Answer:
$0.0238
Explanation:
The energy you need to increase the temperature of water from 20°C to 100°C is obtained from:
Q = C×m×ΔT
Where Q is the energy, C is specific heat of water (4.184J/g°C), m is mass of water (2.00x10²g - Density of water 1g/mL), ΔT is change in temperature (100.0°C - 20.0°C)
Replacing:
Q = 4.184J/g°C × 2.00x10²g × 80.0°C
Q = 66944J = 66.944kJ
As you are assuming the energy of combustion will be just 50.0% to heat the water the energy you need is 66.944kJ × 2 = 133.888kJ
The combustion of methane is:
CH4(g) + 2O2(g) ⟶ CO2(g) + 2H2O(l) ΔH = −890.8kJ
That means 1 mole of methane produce 890.8kJ. As you need 133.888kJ, moles of methane are:
133.888kJ × (1 mol CH₄ / 890.8kJ) = 0.150 moles of CH₄.
Using PV = nRT, moles of 15.0ft³ (424.8L) at 20.0°C (293.15K) and 1.00atm:
1.00atmₓ424.8L = moles CH₄ₓ0.082atmL/molKₓ293.15K
17.67 = moles CH₄
As 17.67 moles of CH₄ cost $2.80, the cost of 0.150 moles of CH₄ is:
0.150 moles CH₄ ₓ ($2.80 / 17.67 moles) =
$0.0238Reactive oxygen species (ROS) are unstable, or reactive, compounds that result from the partial reduction of oxygen. ROS can cause damage to molecules, including membrane lipids and nucleic acids, and may be associated with some diseases. Which of these compounds are reactive oxygen species? Choose all that apply.
a. OH
b. OH-
c. O2-
d. H2O
e. H2O2
f. H-
A chemistry student weighs out 0.306 g of citric acid (H3C6H5O7) , a triprotic acid, into a 250. mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1000 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the equivalence point. Be sure your answer has the correct number of significant digits
Answer:
THE VOLUME OF NaOH NEEDED TO BE ADDED TO CITRIC ACID TO REACH THE EQUIVALENT POINT IS 4.725 L
Explanation:
The titration is between citric acid (H3C6H507) and NaOH
mass of citric acid = 0.306 g
Volume of citric acid = 250 mL = 250 /1000 = 0.25 L
Concentration of NaOH = 0.1000 M
Volume = unknown
First calculate the molar mass of citric acid
( 1 * 3 + 12* 6 + 1*5 + 16*7) = (4 + 72 + 5 + 112) = 193 g/mol
Since,
Concentration in moles/dm3 = concentration in g/dm3 / RMM
So the molarity of citric acid is:
Molarity = 0.306g / 0.25dm3 / Rmm
Molarity = 1.224g/dm3 / 193 g/mol
Molarity = 0.0063 M
Equation for the reaction is:
C3H5O(COOH)3 + 3NaOH → Na3C3H5O(COO)3 + 3H2O
Using the formula:
CaVa / CbVb = na/ nb
Ca = 0.0063 M
Cb = 0.1000 M
Va = 0.25 L
Vb = unknown
na = 1
nb = 3
Vb = Ca Va nb/ Cb na
Vb = 0.0063 * 0.25 * 3 / 0.1000 * 1
Vb = 0.4725 / 0.1000
Vb = 4.725 L
The volume of NaOH needed to reach the equivalent point is therefore 4.725 L
A sample of carbon dioxide gas at a pressure of 879 mm Hg and a temperature of 65°C, occupies a volume of 14.2 liters. Of the gas is cooled at constant pressure to a temperature of 23°C, the volume of the gas sample will be
Answer:
The correct answer is 12.43 Liters.
Explanation:
Based on the given question, the volume V₁ occupied by the sample of carbon dioxide gas is 14.2 liters at temperature (T₁) 65 degree C or 65+273 K = 338 K.
The gas is cooled at a temperature (T₂) 23 degree C or 273+23 K = 296 K
The volume of the gas (V₂) after cooling can be determined by using the formula,
V₁/T₁ = V₂/T₂
14.2/338 = V₂/296
0.0420 = V₂/296
V₂ = 0.0420 * 296
V₂ = 12.43 Liters.
Which option describes a similarity and a difference between isotopes of an element? A. same atomic number; different number of protons B. same number of protons; different atomic number C. same atomic number; different mass number D. same mass number; different atomic number E. same number of neutrons; same number of protons
Answer:
c
Explanation:
Commercially available hot packs are simple in design: a pouch with water on one side, isolated by a barrier from a specific salt on the other side. When the barrier is broken, the salt and water mix and the solution becomes hot. Select the statement that is true about the reaction occurring in hot packs.A. The hot pack absorbs heat from the environment.
B. The reaction between the salt and water is exothermic.
C. The reaction between the salt and water is endothermic.
D. The reaction between the salt and water is neither endothermic nor exothermic.
Answer:
b :)
Explanation:
an exothermic reaction is when heat/light is produced. heart is produced from this reaction so it is exothermic
The correct answer is option c. The reaction between salt and water is endothermic.
How are salt and water endothermic?Chemical reaction
Salt is a hygroscopic material that attracts water and heat from its surroundings. This is why leather shoes are "dry" and wrinkled when covered with salt. This type of reaction is known as an endothermic reaction, which is a chemical reaction that absorbs heat.
Endothermic reaction: A chemical reaction that absorbs heat is called an endothermic reaction. The temperature will drop. For example, (i) heating nitrogen and oxygen together to a temperature of about 3000 ° C produces nitrogen oxide gas. N2 + O2 + heat → 2NO (g)
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Pyruvate is the end product of glycolysis. Its further metabolism depends on the organism and on the presence or absence of oxygen. Draw the structure of the product from each reaction as it would exist at pH 7. Include the appropriate hydrogen atoms. Reaction A: aerobic conditions in humans or yeast
The given question is incomplete. The image present in the question for Reaction A is attached below along with the answer.
Explanation:
Pyruvate molecule reacts with Coenzyme A in the presence of oxygen and it results in the formation of acetyl Coenzyme A and carbon dioxide.
The enzyme pyruvae dehydrogenase helps in catalyzing this reaction. As in this biochemical reaction [tex]NAD^{+}[/tex] gets converted into NADH.
This reaction is shown in the image attached below.
1. Reaccionan 9.7 Kg de un mineral de níquel al 70% con 8L de una solución de ácido fosfórico al 60% y con una densidad de 1.36g/ml.
Answer:
The reaction produces 201.4 g of hydrogen gas and 12.2 kg of Nickel Phosphate.
Explanation:
English Translation
9.7 Kg of a 70% nickel mineral react with 8L of a 60% phosphoric acid solution and with a density of 1.36g / ml.
Solution
The problem doesn't seen to be complete as it doesn't ask a question in the end. But, we will just calculate the amount of each product expected to cover the grounds.
The balanced chemical reaction between Nickel and Phosphoric acid is given as
3Ni + 2H₃PO₄ → 3H₂ + Ni₃(PO₄)₂
We need to first obtain the limiting reagent, that is, the reagent that is used up during the reaction and is in short supply. This reagent determines the amount of products that will be formed.
Mass of nickel that is present at the start = 70% of 9.7 kg = 6.79 kg
Mass of Phosphoric acid present at the start of the reaction = 60% of (8000 mL × 1.36 g/mL) = 6528 g = 6.528 kg
Converting both of these to number of moles
Number of moles = (mass)/(Molar mass)
For nickel,
Mass = 6.79 kg = 6790 g
Molar mass = 58.6934 g/mol
Number of moles at the start = (6790/58.6934) = 115.7 moles
For Phosphoric acid
Mass = 6528 g
Molar mass = 97.994 g/mol
Number of moles = (6528/97.994) = 66.6 moles
3 moles of Ni reacts with 2 moles of H₃PO₄
From the number of moles present initially, shows that Phosphoric acid is in limited supply and is the limiting reagent.
From the stoichiometric balance of the reaction
2 moles of H₃PO₄ gives 3 moles of H₂
66.6 moles of H₃PO₄ will give (66.6×3/2) of H₂, that is, 99.9 moles of H₂.
Mass of H₂ liberated from the reaction = (Number of moles) × (molar mass) = 99.9 × 2.016 = 201.3984 g = 201.4 g
2 moles of H₃PO₄ gives 1 mole of Ni₃(PO₄)₂
66.6 moles of H₃PO₄ will give (66.6×1/2) of Ni₃(PO₄)₂, that is, 33.3 moles of Ni₃(PO₄)₂.
Mass of Ni₃(PO₄)₂ produced from the reaction = (Number of moles) × (molar mass) = 33.3 × 366.02 = 12,188.466 g = 12.2 kg
Hope this Helps!!!
4-Methylphenol, CH3C6H4OH (pKa 10.26), is only slightly soluble in water, but its sodium salt, CH3C6H4O-Na , is quite soluble in water. Describe the solubility of 4-methylphenol in solutions of sodium hydroxide, sodium bicarbonate (NaHCO3), and sodium carbonate (Na2CO3). The pKa values for the conjugate acids of sodium hydroxide, sodium bicarbonate (NaHCO3), and sodium carbonate (Na2CO3) are 15.7, 6.36, and 10.33, respectively.
Explanation:
We know that more is the [tex]pK_{a}[/tex] value, weaker will be the acid. Also, an acid completely dissociates into ions in an aqueous base solution when [tex]pK_{a}[/tex] of conjugate acid of base is greater than acid.
4-methylphenol [tex](CH_{3}C_{6}H_{4}OH)[/tex] ([tex]pK_{a} = 10.26[/tex]) is quite soluble in its sodium salt. In NaOH, the dissociation will be as [tex]Na^{+}[/tex] and [tex]OH^{-}[/tex] ions as NaOH is a strong base.
Therefore, 4-methylphenol will readily dissolve in NaOH solution.
As, [tex]NaHCO_{3}[/tex] is not a strong base but as 4-Methylphenol forms a sodium salt hence, it will have a low solubility as compared to NaOH.
Whereas [tex]Na_{2}CO_{3}[/tex] is not a base but when dissolved in water it shows basic character as it produces NaOH (strong base) and [tex]H_{2}CO_{3}[/tex] (weak acid). As a result, the solution gets basic. Hence, 4-methylphenol will readily dissolve in [tex]Na_{2}CO_{3}[/tex].
where are chemicals found in the home?
a. only in the bathroom
b. only in locked cabinets
c. in every room
d. only in the kitchen
Answer:
c
Explanation:
chemicals can be found in every part of our lives
Suppose that while you're in the lab performing a simple distillation you encountered one of the following errors: The components within the mixture, isopropanol and dichloromethane, distilled well below their boiling point. Poor separation between isopropanol and dichloromethane was observed. The initial volume of the distillation mixture has decreased significantly, almost dry, but no distillate was collected.
Answer:
Isopropanol and dichloromethane, distilled well below their boiling point.
Explanation:
The best way to separate isopropanol and dichloromethane is the method of fractional distillation. In this method, different compounds separate from each other due to difference in boiling. The boiling point of dichloromethane is 39.6 degree Celsius which is lower than the boiling point of isopropanol which is 82.5 degree Celsius. So dichloromethane will be evaporated when the temperature reaches to 40 degree Celsius and separated from isopropanol before reaching its boiling point.
The half-life of radium-226 is 1590 years. (a) A sample of radium-226 has a mass of 50 mg. Find a formula for the mass of the sample that remains after t years. (b) Find the mass after 500 years correct to the nearest milligram. (c) When will the mass be reduced to 40 mg
Answer:
Explanation:
a )
m = m₀ [tex]e^{-\lambda t[/tex]
m is mass after time t . original mass is m₀ , λ is disintegration constant
λ = .693 / half life
= .693 / 1590
= .0004358
m = m₀ [tex]e^{- 0.0004358 t}[/tex]
b )
m = 50 x [tex]e^{-.0004358\times 500}[/tex]
= 40.21 mg .
c )
40 = 50 [tex]e^{-.0004358t[/tex]
.8 = [tex]e^{-.0004358t[/tex]
[tex]e^{.0004358t[/tex] = 1.25
.0004358 t = .22314
t = 512 years .
A semipermeable sac containing 4% NaCl, 9% glucose, and 10% albumin is suspended in a solution with the following composition: 10% NaCl, 10% glucose, and 40% albumin. Assume that the sac is permeable to all substances except albumin. State whether each of the following will (a) move into the sac, (b) move out of the sac, or (c) not move.
glucose: a. moves into sac
water: b. moves out of sac
albumin: c; does not move
NaCl: a; moves into sac
Answer:
Glucose: (a) moves into sac
Water: (b) moves out of sac
Albumin: (c) does not move
NaCl: (a) moves into sac
Explanation:
A semi-permeable membrane is a membrane that allow certain molecules or ions to pass through by diffusion.
Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration until equilibrium is attained. A special form of diffusion known as osmosis transports water molecules across a semi-permeable membrane.
Osmosis is the movement of water molecules from a region lower solute concentration (high water molecules concentration) to a region of higher solute concentration (low water molecules concentration) until equilibrium is attained.
From the above definitions and the given data;
Glucose concentration is higher in solution outside the sac, thus, glucose molecules will move into the sac.
Water molecules are higher in the sac as a result of the lower concentration of solutes, therefore, water molecules will move out of the sac into the solution outside.
Since the sac is impermeable to albumin, it does not move.
NaCl concentration is lower in the sac, therefore, it will move ro the solution outside into the sac.
Glucose will move into the sac, water will move out of the sac, albumin will neither move in nor out, and NaCl will move into the sac.
The molecules of each of the substances will move by diffusion from the region of higher concentration to the region of lower concentration of each substance as long as there is a permeable membrane. Water, on the other hand, will move by osmosis from the region of high to low water potential through a permeable membrane. Regions with higher concentrations of substances usually have low water potentials and vice versa.Thus, both glucose and NaCl molecules will diffuse from the solution into the sac, and water molecules will move from the sac into the surrounding solution. Since the sac is not permeable to albumin, then the movement in or out is inhibited.
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BASIC CALCULATIONS IN SPECTROSCOPY
1. Calculate the %T of light at 425nm if the light entering the cell is 200 lumens and the amount of light exiting the cell is 50 lumens.
2. Calculate the absorbance of the above problem.
Answer: 25%
Explanation:
1. Transmittance, T= P/P0
Where P = light exiting the cell
P0 = light entering the cell
Therefore %T = P/P0 ×100
= 50/200×100
=25%
2. Absorbance, A= -log(T)
But T= 0.25
Therefore A= -log(0.25)
= 0.6020
At 25 oC, the rate constant for the first-order decomposition of a pesticide solution is 6.40 x 10-3 min-1. If the starting concentration of pesticide is 0.0314 M, what concentration will remain after 62.0 minutes at 25 oC? 3.12 x 10-2 M 47.4 M 2.11 x 10-2 M 4.67 x 10-2 M 8.72 M
Answer:
[tex]2.11\ * 10^{-2}[/tex] is the correct answer to the given question.
Explanation:
Given k=6.40 x 10-3 min-1.
According to the first order reaction .
The concentration of time can be written as
[tex][\ A\ ]\ = \ [\ A_{0}\ ] * e \ ^\ {-kt}[/tex]
Here [tex][\ A\ ]_{0}[/tex] = Initial concentration.
So [tex][\ A\ ]_{0}= 0.0314 M[/tex]
Putting this value into the above equation.
[tex]0.0314 \ *\ e^{6.40 x 10^{-3} \ * \ 62.0 }[/tex]
=0.211 M
This can be written as
[tex]=\ 2.11 *\ 10^{-2}[/tex]
Isomer such as acetic acid and methyl formate have
Answer:
C
Explanation:
This is the definition of an isomer.
why does Portland have moderate climate
Answer:
Due to its location, Portland has a moderate climate. Also, which portland are you talking about? Portland Oregon or Portland Maine. Portland Oregon has a much more rainy climate, so I would say Maine has a better climate.
Explanation:
Which of the following best describe an atomic number? An element identity is defined by its atomic number this means it represents the number of
a)Atomic number is the number of protons in the nucleus of an atom.
b)atomic number represents the number of protons
An element's identity is defined by its atomic number; this means it represents the number of protons in its nucleus.
The question is incomplete, the complete question is;
Which of the following best describes an atomic number? An element's identity is defined by its atomic number; this means it represents the number of
A) protons plus neutrons in its nucleus.
B) electrons in the element.
C) protons in its nucleus.
D) neutrons in its nucleus.
The subatomic particles in the atom are;
ElectronsProtonsNeutronsNeutrons and protons are contained in the nucleus hence they are collectively called nucleons.
Electrons are found in the orbits. The number of protons must be equal to the number of electrons for the atom to be electrically neutral.
The number of protons in an atom or atomic number serve as a means of identifying an atom.
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An ethylene glycol solution contains 21.4 g of ethylene glycol (C2H6O2) in 97.6 mL of water.
Required:
a. Determine the freezing point of the solution. Express you answer in degrees Celsius. (Assume a density of 1.00 g/mL for water.)
b. Compute the boiling point of the solution. (Assume a density of 1.00 g/mL for water.)
Answer:
a. TFinal = -6.57°C
b. Tfinal = 101.80°C
Explanation:
When a solute is added to a solvent producing an ideal solution, the freezing point of the solution decreases with regard to pure solvent. Also, boiling point increases with regard to pure solvent.
The formulas are:
Freezing point:
ΔT = Kf×m×i
Where Kf is freezeing point depression constant of water (1.86°C/m), m is molality of solution and i is van't Hoff factor (1 for ethylene glycol).
Boiling point:
ΔT = Kb×m×i
Where K is freezeing point depression constant of water (0.51°C/m), m is molality of solution and i is van't Hoff factor (1 for ethylene glycol).
Moles of 21.4g of ethylene glycol (Molar mass: 62.07g/mol) are:
21.4g C₂H₆O₂ ₓ (1mol / 62.07g) = 0.345 moles
And kg of 97.6mL of water = 97.6g are 0.0976kg. Molality of the solution is:
0.345mol / 0.0976kg = 3.5325m
Replacing in the formulas:
a. Freezing point:
ΔT = 1.86C/m×3.5325m×1
ΔT = 6.57°C
0°C - Tfinal = 6.57°C
TFinal = -6.57°Cb. Boiling point:
ΔT = 0.51°C/m×3.5325m×1
ΔT = 1.80°C
Tfinal - 100°C = 1.80°C
Tfinal = 101.80°C
Which is true regarding a water molecule?
Answer:
Has many answers, but one is that it consists of small polar v shaped molecules with a molecular formula H20.
Explanation:
Water molecules consists of 2 hydrogen atoms bonded with on oxygen atom. Each molecule is electrically neutral but polar, with the center of positive and negative charges located in different places.
Each hydrogen atom has a nucleus consisting of a single positively-charged proton surrounded by a 'cloud' of a single negatively-charged electron and the oxygen atom has a nucleus consisting of eight positively-charged protons and eight uncharged neutrons surrounded by a 'cloud' of eight negatively-charged electrons.
Hoped this helped!
An unknown compound, B, has the molecular formula C7H12. On catalytic hydrogenation 1 mol of B absorbs 2 mol of hydrogen and yields 2-methylhexane. B has significant IR absorption band at about 3300 and 2200 cm-1. Which compound best represents B?
Answer:
5-methylhex-1-yne//5-methylhex-2-yne//2-methylhex-3-yne
Explanation:
We have to start with the information on the IR spectrum. The signal at 3300 is due to a C-H bend sp carbon and the signal in 2200 is due to the stretch carbon-carbon. Therefore we will have an alkyne. Now if we have 2-methylhexane as the product of hydrogenation we have several options to put the triple bond. Between carbons 1 and 2 (5-methylhex-1-yne), between carbons 2 and 3 (5-methylhex-2-yne) and between carbons 3 and 4 (2-methylhex-3-yne). On carbon 5 we have a tertiary carbon therefore we dont have any other options.
See figure 1
I hope it helps!
A 8.00g of a certain Compound X, known to be made of carbon, hydrogen and perhaps oxygen, and to have a molecular molar mass of 44./gmol, is burned completely in excess oxygen, and the mass of the products carefully measured: product mass carbon dioxide 24.01g water 13.10g Use this information to find the molecular formula of X.
Answer:
C3H6.
Explanation:
Data obtained from the question:
Mass of the compound = 8g
Mass of CO2 = 24.01g
Mass of H2O = 13.10g
Next, we shall determine the mass of C, H and O present in the compound. This is illustrated below:
Molar Mass of CO2 = 12 + (2x16) = 44g/mol
Molar Mass of H2O = (2x1) + 16 = 18g/mol
Mass of C in compound = Mass of C/Molar Mass of CO2 x 24.01
=> 12/44 x 24.01 = 6.5g
Mass of H in the compound = Mass of H/Molar Mass of H2O x 13.1
=> 2x1/18 x 13.1 = 1.5g
Mass of O in the compound = Mass of compound – (mass of C + Mass of H)
=> 8 – (6.5 + 1.5) = 0
Next, we shall determine the empirical formula of the compound. This is illustrated below:
C = 6.5g
H = 1.
Divide by their molar mass
C = 6.5/12 = 0.54
H = 1.4/1 = 1.
Divide by the smallest
C = 0.54/0.54 = 1
H = 1/0.54 = 2
Therefore, the empirical formula is CH2
Finally, we shall determine the molecular formula as follow:
The molecular formula of a compound is a multiple of the empirical formula.
Molecular formula = [CH2]n
[CH2]n = 44
[12 + (2x1)]n = 44
14n = 44
Divide both side by 14
n = 44/14
n = 3
Molecular formula = [CH2]n = [CH2]3 = C3H6
Therefore, the molecular formula of the compound is C3H6
Who proposed the plum pudding model and what does it say about the structure of the atom
Answer:
J. J. Thomson
Explanation:
First proposed by J. J. Thomson in 1904 soon after the discovery of the electron, but before the discovery of the atomic nucleus, the model tried to explain two properties of atoms then known: that electrons are negatively-charged particles and that atoms have no net electric charge.
A 20.0-mL sample of lake water was acidified with nitric acid and treated with excess KSCN to form a red complex (KSCN itself is colorless). The solution was then diluted to 50.0-mL and put in a 1.00 cm pathlength cell, where it yielded an absorbance of 0.345. For comparison, a 5.0-mL reference sample of 4.80 x 10-4 M Fe3 was treated with HNO3 and KSCN and diluted to 50.0 mL. The reference solution was also placed in a 1.00-cm cell and gave an absorbance of 0.512. What is the concentration of Fe3 in Jordan Lake
Answer:
8.09x10⁻⁵M of Fe³⁺
Explanation:
Using Lambert-Beer law, the absorbance of a sample is proportional to its concentration.
In the problem, the Fe³⁺ is reacting with KSCN to produce Fe(SCN)₃ -The red complex-
The concentration of Fe³⁺ in the reference sample is:
4.80x10⁻⁴M Fe³⁺ × (5.0mL / 50.0mL) = 4.80x10⁻⁵M Fe³⁺
Because reference sample was diluted from 5.0mL to 50.0mL.
That means a solution of 4.80x10⁻⁵M Fe³⁺ gives an absorbance of 0.512
Now, as the sample of the lake gives an absorbance of 0.345, its concentration is:
0.345 × (4.80x10⁻⁵M Fe³⁺ / 0.512) = 3.23x10⁻⁵M.
As the solution was diluted from 20.0mL to 50.0mL, the concentration of Fe³⁺ in Jordan lake is:
3.23x10⁻⁵M Fe³⁺ × (50.0mL / 20.0mL) = 8.09x10⁻⁵M of Fe³⁺
The concentration of Fe³⁺ in Jordan Lake is = 8.09* 10⁻⁵ M
According to Lambert-Beer law ;The rate of absorbance of a sample is directly proportional to concentration of the sample
The reaction that produces a red complex
Fe³⁺ + KScN ----> Fe ( SCN )₃ ( red complex )
First step: Determine the Concentration of Fe³⁺ in reference sample
= 4.80x10⁻⁴ * ( 5.0 / 50.0 ) = 4.80 * 10⁻⁵M
reference sample was diluted from 5.0 mL to 50.0 mL
∴ Concentration of 4.80 * 10⁻⁵M has an absorbance = 0.512
Given that Lake sample absorbance = 0.345
Next step : Determine the concentration of the lake sample
Concentration of lake sample :
= absorbance of lake sample * ( conc of reference sample / absorbance )
= 0.345 * ( 4.80* 10⁻⁵ / 0.512 ) = 3.23* 10⁻⁵M.
Final step : Determine the concentration of Fe³⁺ in Jordan lake
= 3.23 * 10⁻⁵ * ( 50.0mL / 20.0mL) = 8.09* 10⁻⁵ M
Note : Solution was diluted from 20.0 mL to 50.0 mL
Hence we can conclude that The concentration of Fe³⁺ in Jordan Lake is = 8.09* 10⁻⁵ M .
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Gold can be separated from sand by panning or by a sluice-box. In panning, water is mixed with the sand and the resulting slurry is swirled in a shallow, saucer-shaped metal pan. In the sluice-box technique, running water is passed over an agitated sand- gold mixture. What physical property and what technique make this separation possible?
Answer:
Decantation by means of difference in relative densities.
Explanation:
The specific gravity (relative density) of the gold to the soil/sand is the physical property exploited in panning gold. The particles with lower density would float whilst the heavier gold sinks lower to the bottom of the pan by gravity and is decanted off.
I hope this explanation is easy to comprehend.
A boy with pneumonia has lungs with a volume of 1.7 L that fill with 0.070 mol of air when he inhales. When he exhales, his lung volume decreases to 1.3 L. Enter the number of moles of gas that remain in his lungs after he exhales. Assume constant temperature and pressure.
Answer:
0.053moles
Explanation:
Hello,
To calculate the number of moles of gas remaining in his after he exhale, we'll have to use Avogadro's law which states that the volume of a given mass of gas is directly proportional to its number of moles provided that temperature and pressure are kept constant. Mathematically,
V = kN, k = V / N
V1 / N1 = V2 / N2= V3 / N3 = Vx / Nx
V1 = 1.7L
N1 = 0.070mol
V2 = 1.3L
N2 = ?
From the above equation,
V1 / N1 = V2 / N2
Make N2 the subject of formula
N2 = (N1 × V2) / V1
N2 = (0.07 × 1.3) / 1.7
N2 = 0.053mol
The number of moles of gas in his lungs when he exhale is 0.053 moles
If a pork roast must absorb 1500 kJkJ to fully cook, and if only 14% of the heat produced by the barbeque is actually absorbed by the roast, what mass of CO2CO2 is emitted into the atmosphere during the grilling of the pork roast?
You need to know the amount of heat generated by the combustion reaction.
Assuming propane as fuel, you can use thiis data:
C3H8(g)+5O2(g)---3CO2(g)+4H2O(g) ΔH= -2217 KJ
So when 3 moles of CO2 is emmitted 2217 kJ of heat is produced.
The molar wegiht of CO2 is 12 g/mol + 2 * 16 g/mol = 44 g/mol.
Then 3 mol * 44 g / mol = 132 g of CO2 are produced with 2217 kJ of heat.
Now you have to calculate how much energy you need to produce if only 12% is abosrbed by the pork
Energy absorbed by the pork = 12% * total energy =>
total energy = energy absorbed by the pork / 0.12 = 1700 kJ / 0.12 = 14,166.67 kJ.
Now, state the proportion:
132 g CO2 / 2217 kJ = x / 14,166.7 kJ =>
x = 14,166.67 * 132 / 2217 = 843.48 g CO2.
Answer: 843 g of CO2
A certain metal forms a soluble nitrate salt M(NO3)3. Suppose the left half cell of a galvanic cell apparatus is filled with a 3.0mM solution of M(NO3)3 and the right half cell with a 3.0M solution of the same substance. Electrodes made of M are dipped into both solutions and a voltmeter is connected between them. The temperature of the apparatus is held constant at 20.0 C.
Required:
a. Which electrode will be positive?
b. What voltage will the voltmeter show? Assume its positive lead is connected to the positive electrode.
Answer:
1.The electrode on the right is positive
2. 0.058V
Explanation:
The above cell is a concentration cell.
A concentration cell is an electrolytic cell that is made of two half-cells with the same electrodes, but differs in concentrations of the solutions. A concentration cell functions by diluting the more concentrated solution and concentrating the more dilute solution, creating a voltage as the cell reaches an equilibrium thereby transferring the electrons from the cell with the lower concentration to the cell with the higher concentration.
In the above cell, electrons flow from the left electrode (less concentrated) to the right electrode (more concentrated). Therefore, the right electrode is the positive electrode (cathode).
Part 2: Please, see the attachment below for the calculations.
a introduction paragraph about coal and natural gas
Answer:
here is ur and
Explanation:
Coal, oil and natural gas are called fossil fuels. Fossil fuels are burned to make energy. Burning fossil fuels also releases CO2 (carbon dioxide) gas into the atmosphere. Most air pollutants (such as sulfur dioxide) don't stay in the atmosphere very long.
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A red blood cell is placed into each of the following solutions. Indicate whether crenation, hemolysis, or neither will occur. Solution A: 3.75 % (m/v) NaCl Solution B: 1.92 % (m/v) glucose Solution C: distilled H2O Solution D: 9.03 % (m/v) glucose Solution E: 5.0% (m/v) glucose and 0.9% (m/v) NaCl
Answer:
A. The cell will undergo crenation
B. The cell will undergo hemolysis
C. The cell will undergo hemolysis
D. The cell will undergo crenation.
E. The cell will undergo neither crenation nor hemolysis
Explanation:
A hypotonic solution is a solution in which the concentration of solutes is greater inside the cell than outside the cell.
A hypertonic solution is a solution in which the concentration of solutes is greater outside the cell than inside the cell.
An isotonic solution is a solution in which the concentration of solution is the same outside and inside of the cell. A solution with 5% (m/v) glucose and 0.9% (m/v) NaCl is an isotonic solution.
When a red blood cell is placed in a hypotonic solution, it will swell and burst. This is known as hemolysis.
When placed in a hypertonic solution, a red blood cell will lose water and shrivel. This is is known as cremation.
When a red blood cell is placed in an isotonic solution, neither hemolysis or crenation occurs as there is no net movement of water across the cell's membrane.
A: 3.75 % (m/v) NaCl Solution is a hypertonic solution. The cell will undergo crenation
B: 1.92 % (m/v) glucose Solution is hypotonic. The cell will undergo hemolysis
C: Distilled H2O Solution is a hypotonic solution. The cell will undergo hemolysis
D: 9.03 % (m/v) glucose Solution is a hypertonic solution. The cell will undergo crenation
E: 5.0% (m/v) glucose and 0.9% (m/v) NaCl are both isotonic solutions. The cell will undergo neither hemolysis not crenation.
Solution A (3.75% NaCl): Crenation
Solution B (1.92% glucose): HemolysisSolution C (Distilled H2O): HemolysisSolution D (9.03% glucose): CrenationSolution E (5.0% glucose and 0.9% NaCl): CrenationWhat is the SolutionTo find out if a red blood cell will shrink, burst, or stay the same when placed in a solution, we have to think about how concentrated the solution is compared to the red blood cell.
A red blood cell has a normal concentration of about 0. 9% salt or 0. 3% sugar Solutions that have more concentrated substances are called hypertonic, while solutions that have less concentrated substances are called hypotonic.
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