Answer:
Chemical
Explanation:
Whenever "burns" is being used, most of the time it is a chemical change
Answer:
chemical change
Explanation:
it's a chemical change because when gas burn it produces water and carbon dioxide
Which of the following formulas represents an ionic compound?
1.HI 2.HCI 3.LiCI 4.SO2
Answer:
Numbers 4,3
Explanation:
Ionic bond is between nonmental and metals
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
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 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
Which of the following viewed the atom as having a nucleus made up of protons and neutrons,with electrons orbiting the nucleus in fixed, stable orbits, much like the planets orbit the sun?
The correct answer is C. Bohr's model
Explanation:
Bohr's model of the atom developed in 1913 proposed each atom contained a nucleus with protons and neutrons. Also, there were electrons that orbited the nucleus. About this, Niels Bohr proposed the orbits of electrons were similar to those of planets around the sun; however, these did not occur due to gravity but to attraction forces. This model integrated new accurate ideas about the atom. However, this model was still inaccurate because particles in an atom are electrically charged and electrons do not orbit in fixed stable orbits and cannot be compared to the movement of planets around a star.
Answer:
Bohr's model
Explanation:
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.
One of the many remarkable enzymes in the human body is carbonic anhydrase, which catalyzes the interconversion of carbon dioxide and water with bicarbonate ion and protons. If it were not for this enzyme, the body could not rid itself rapidly enough of the CO2 accumulated by cell metabolism. The enzyme catalyzes the dehydration (release to air) of up to 107 CO2 molecules per second. Which components of this description correspond to the terms enzyme, substrate, and turnover number?
Answer:
Enzyme is carbonic anhydrase
Substrate is [tex]CO_2[/tex]
Turnover number is [tex]10^{7}[/tex]
Explanation:
An enzyme is used by a living organism as a catalyst to perform a specific biochemical reaction.
A substrate is a molecule upon which an enzyme acts.
Turnover number refers to the number of substrate molecules transformed by a single enzyme molecule per minute. Here, the enzyme is the rate-limiting factor.
Here,
Enzyme is carbonic anhydrase
Substrate is [tex]CO_2[/tex]
Turnover number is [tex]10^{7}[/tex]
A temperature of 50°F is equal to °C.
Answer:
CONVERT IT:
50°F is equal to 10°C
Answer:
10 degrees Celsius
Explanation:
(50°F − 32) × 5/9 = 10°C
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.
Isomer such as acetic acid and methyl formate have
Answer:
C
Explanation:
This is the definition of an isomer.
A student sets up the following equation to convert a measurement. (The ? stands for a number the student is going to calculate.) Fill in the missing part of this equation. Note: your answer should be in the form of one or more fractions multiplied together. (23. Pa cm^3)____?kPa . m^3
Answer:
The correct answer will be "-6.7 × 10¹⁰ kg.m/s".
Explanation:
The required conversions are:
⇒ [tex]1 \ kg=1000 \ g[/tex]
⇒ [tex]1 \ m=100 \ cm[/tex]
Now,
The complete conversion will be:
= [tex][-6.7\times 10^5 \ \frac{kg \ m}{s} ]\times [\frac{10^3 \ g}{kg}\times \frac{10^2 \ cm}{1 \ m}][/tex]
On cancelling the terms, we get
= [tex]-6.7\times 10^{10} \frac{kg \ m}{s}[/tex]
So that the missing terms will be [tex][\frac{10^3 \ g}{kg}\times \frac{10^2 \ cm}{1 \ m}][/tex] and [tex][-6.7\times 10^{10}\frac{kg \ m}{s}][/tex]
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
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.
Learn more; https://brainly.com/question/18460120
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]
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) =
$0.0238Draw every stereoisomer for 1-bromo-2-chloro-1,2-difluorocyclopentane. Use wedge-and-dash bonds for the substituent groups, and be sure that they are drawn on the outside of the ring, adjacent to each other. The skeletal structure of one molecule is included to indicate the proper format.
Answer:
Explanation:
The objective here is mainly drawing the diagrams of every stereoisomer for 1-bromo-2-chloro-1,2-difluorocyclopentane.
Stereoisomerism is the difference of the spatial arrangement of atoms in a molecule or a compound with the same molecular formula.
For 1-bromo-2-chloro-1,2-difluorocyclopentane.
We have the stereoisomers as follows:
(1R,2S)-1-bromo-2-chloro-1,2-difluorocyclopentane.
(1S,2R)-1-bromo-2-chloro-1,2-difluorocyclopentane.
(1S,1S)-1-bromo-2-chloro-1,2-difluorocyclopentane.
(1R,1R)-1-bromo-2-chloro-1,2-difluorocyclopentane.
Their diagrams are drawn and shown in the attached file below in the order with which they are listed above.
A 100.0 mL sample of 0.300 M NaOH is mixed with a 100.0 mL sample of 0.300 M HNO 3 in a coffee cup calorimeter. If both solutions were initially at 35.00°C and the temperature of the resulting solution was recorded as 37.00°C, determine the ΔH° rxn (in units of kJ/mol NaOH) for the neutralization reaction between aqueous NaOH and HCl. Assume 1) that no heat is lost to the calorimeter or the surroundings, and 2) that the density and the heat capacity of the resulting solution are the same as water.
Answer:
THE STANDARD HEAT OF NEUTRALIZATION OF THE BASE SODIUM HYDROXIDE BY THE ACID HYDROGEN TRIOXONITRATE V ACID IS -56 kJ / mol.
Explanation:
Volume of 0.3 M NaOh = 100 mL
Volume of 0.3 M HNO3 = 100 mL
Initail temp of NaOH and HNO3 = 35 °C = 35 + 273 K = 308 K
Final temp. of mixture = 37 °C = 37 + 273 K = 310 K
We can make the following assumptions form the question given:
1. specific heat of the reaction mixture is the same as the specific heat of water = 4.2 J/g K
2. the toal mass of the reaction mixture is 200 mL = 200 g since no heat is lost to the calorimeter or surrounding.
3. initail temperature of the reaction mixture is equal to the average temperature of the two reactant solutions
= ( 308 + 308 /2) = 308 K
4. Rise in temeperature for the reaction = 310 -308 K = 2 K
Then the total heat evolved during the reaction = mass * specifc heat capacity * temperature change
Heat = 200 g * 4.2 J/g K * 2 K
Heat = 1680 J
EQUATION FOR THE REACTION
HNO3 + NaOH -------> NaNO3 + H20
From the equation, 1 mole of HNO3 reacts with 1 mole of NaOH to prouce mole of water.
100 mL of 0.5 M HNO3 contains 100 * 0.3 /1000 = 0.03 mole of acid
This result is same for the base NaOH = 0.03 mole of base
So therefore,
0.03 mole of acid will react with 0.03 mole of base to produce 0.03 mole of water to evolved 1680 J of heat energy.
The production of 1 mole of water will evolve 1680 / 0.03 J of heat
= 56 000 J or 56 kJ of heat energy per mole of water.
So therefore, 1the standard heat of neutralization of sodium hydroxide by trioxoxnitrate V acid is -56 kJ/mol.
How many moles of PC15 can be produced from 51.0 g of Cl2 (and excess P4)?
Express your answer to three significant figures and include the appropriate units.
LIT....ITS NOT .227 or .228!!!!
Answer:
0.287 mole of PCl5.
Explanation:
We'll begin by calculating the number of mole in 51g of Cl2. This is illustrated below:
Molar mass of Cl2 = 2 x 35.5 = 71g/mol
Mass of Cl2 = 51g
Number of mole of Cl2 =..?
Mole = Mass /Molar Mass
Number of mole of Cl2 = 51/71 = 0.718 mole
Next, we shall write the balanced equation for the reaction. This is given below:
P4 + 10Cl2 → 4PCl5
Finally, we determine the number of mole of PCl5 produced from the reaction as follow:
From the balanced equation above,
10 moles of Cl2 reacted to produce 4 moles of PCl5.
Therefore, 0.718 mole of Cl2 will react to produce = (0.718 x 4)/10 = 0.287 mole of PCl5.
Therefore, 0.287 mole of PCl5 is produced from the reaction.
what is the balanced equation for calcium sulfate?
Answer:
CaSO4
Explanation:
Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates.
In what unit do we usually measure the force of the earth gravity? Acceleration due to gravity is 9.8/s^2
Answer:
in short weight
Explanation:
weight is mass x gravitational pull on an object
A tank at is filled with of dinitrogen monoxide gas and of boron trifluoride gas. You can assume both gases behave as ideal gases under these conditions. Calculate the mole fraction and partial pressure of each gas, and the total pressure in the tank. Round each of your answers to significant digits.
Answer:
(1). Mole fraction = 0.152 for sulfur tetrafluoride gas.
Mole fraction = 0.848 For dinitrogen monoxide gas.
(2). Partial Pressure for dinitrogen monoxide gas = 187 kPa
Partial Pressure for sulfur tetrafluoride gas = 33.4 kpa.
(3). Total Partial Pressure = 220.4 kpa.
Explanation:
So, we are given the following data or parameters or information in the question above;
• Volume of the tank = 5.00L per tank;
• Temperature of the tank = 7.03°C;
• The mass of the content in the tank =
17.7g of dinitrogen monoxide gas and
7.77g of sulfur tetrafluoride gas.
So, we will be making use of the formulae below to calculate the MOLE FRACTION:
Moles, n= mass/molar mass and mole fraction = n(1)/ n(1) + n(2) per each constituents.
Moles, n1 = 17.7g of dinitrogen monoxide gas/ 44 grams per mole. =0.4023 moles.
Moles, n2 = 7.77g of sulfur tetrafluoride gas/ 108.1 grams per mole. = 0.07188 moles.
Total numbers of moles = n1 + n2 = 0.47415 moles
Mole fraction =0.4023 / 0.47415 = 0.848 of dinitrogen monoxide gas.
Mole fraction = 0.07188/0.47415 = 0.152 of sulfur tetrafluoride gas.
PART TWO: CALCULATE THE PARTIAL PRESSURE AND TOTAL PRESSURE BY USING THE FORMULA BELOW;
pressure × volume = number of moles × gas constant, R × temperature.
Pressure = n × R × T/ V.
For dinitrogen monoxide gas. ;
Partial Pressure = 0.4023 × 8.314 × 280.03 / 5 × 10^-3 = 187 kPa.
For sulfur tetrafluoride gas
Partial Pressure = 0.07188 × 8.314 ( × 280.03 / 5 × 10^-3. = 33.4 kpa.
(3). Total pressure = (187 + 33.4)kpa = 220.4 kpa
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
How do the particles in plasmas compare with the particles in solids?
Answer:
Plasmas and solids are both made up of cation-anion pairs. Solids and plasmas are both made up of electrons and cations. Solids are made up of cation-anion pairs, but plasmas are not.
Answer:
Solids are made up of cation-anion pairs, but plasmas are not.
Explanation:
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.
More on osmosis and diffusion can be found here: https://brainly.com/question/19867503?referrer=searchResults
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:
A student states that the graduated cylinder contains 150 mL of water his statement is
A. A prediction
B. An observation
C. A theory
D. A hypothesis
The correct answer is B. An observation
Explanation:
An observation is defined as a statement or conclusion you made after observing or measuring a phenomenon, this includes statements based on precise instruments. For example, if you conclude a plant grows 2 inches every month by measuring the plant during this time, this is classified as an observation. The conclusion of the student is also an observation because he concludes this after analyzing the volume of the water in the cylinder through the lines in the graduated cylinder, considering the water is just in the middle of 100 mL and 200 mL which indicates there are 150 mL of water.
Answer:
B. An observation
Explanation:
Hello,
Given the illustration, such statements is considered as an observation, since it came up from something the student realized with his/her own eyes, as in the volumetric cylinder the level of the liquid reached 150 mL of water. Predictions are not observed but assumed, theories are stated when experimentation is already deeply studied and hypothesis are assumptions before experimenting.
Regards.
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:
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 chemistry student is given 600. mL of a clear aqueous solution at 37° C. He is told an unknown amount of a certain compound X is dissolved in the solution. The student allows the solution to cool to 21° C. At that point, the student sees that a precipitate has formed. He pours off the remaining liquid solution, throws away the precipitate, and evaporates the water from the remaining liquid solution under vacuum. More precipitate forms. The student washes, dries and weighs the additional precipitate. It weighs 0.084 kg. Using only the information from above, can you calculate the solubility of X at 21° C?If yes, calculate it. Be sure your answer has a unit symbol and the right number of significant figures.
Answer:
The solubility is [tex]S = 0.0014 \ g[/tex]
Explanation:
From the question we are told that
The volume of the solution is [tex]V = 600 mL[/tex]
The initial temperature is [tex]T_i = 37 ^oC[/tex]
The final temperature is [tex]T_f = 21^oC[/tex]
The additional precipitate is [tex]m = 0.084 \ kg = 84 \ g[/tex]
Yes because the solubility of the substance X is the amount of X needed to saturate a unit volume of the solvent (for solubility of a solute to be calculated the solute must be able to saturate the solvent)
now we see that the substance X saturated the solvent because a precipitate was formed which the student threw away
The solubility at 21 ° C is mathematically represented as
[tex]S = \frac{m}{m_w * 100 g \ of water }[/tex]
Mass of water([tex]m_w[/tex]) in the solution is mathematically represented as
[tex]m_w = V * \rho_w[/tex]
Where [tex]\rho = 1 \frac{g}{mL}[/tex]
So
[tex]m_w =600 * 1[/tex]
[tex]m_w =600g[/tex]
So
[tex]S = \frac{84}{600 * 100 g \ of water }[/tex]
[tex]S = 0.0014 \ g[/tex]
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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