Answer:
The percentage yields are as follows :
a) 64.28%
b) 58.03%
c) 69.46%
d) 79.31%
Explanation:
The percentage yield is the ratio of the actual yield of a product to the expected or theoretical yield expressed as a percentage.
Percent yield = actual yield/theoretical yield x 100%
a) from the question, expected yield is 68.3 g whilst the actual yield is 43.9 g
therefore,
Percentage yield = 43.9 g/68.3 g x 100%
= 0.64275 x 100%
= 64.28%
b) From the question, expected yield is 0.0722 mol while the actual yield is 0.0419 mol. Therefore
Percentage yield = 0.0419 /0.0722 x 100%
= 0.58033 x 100%
= 58.03%
c) A limiting reactant is the reactant is is completely used in a recation to form a product. That is, it is the reactant that is not in excess.
From the equation of the reaction :
CH3COOH + CH3CH2OH --> CH3COOCH2CH3 + H2O
1 mole of ethanol reacts with 1 mole of acetic acid to give 1 mole of ethyl acetate.
From the question, ethanol is the limiting reactant because it is not in excess. Hence,
4.29 mole of ethanol should produce 4.29 mole of ethyl acetate (expected yield).
However only 2.98 mol of ethyl acetate is produced (actual yield)
Percentage yield = 2.98mol/4.29 mol x 100%
= 0.69463 x 100%
= 69.46%
d) From the question, acetic acid is in excess hence ethanol is the limiting reactant
therefore from the equation of the reaction:
1 mole of ethanol reacts with 1 mole of acetic acid to give 1 mole of ethyl acetate.
0,58 mol of ethanol should produce 0.58 mol of ethyl acetate (expected yield)
But 0.46 mol of ethyl acetae was produced (actual yield)
Percentage yield = 0.46mol /0.58 mol x 100%
= 0.79310 x 100%
= 79.31%
2. Which change in oxidation number indicates
oxidation?
A) -1 to +2
C) -1 to - 2
B) +3 to +2
D) +2 to -3
Answer:
A)
Explanation:
Increasing of oxidation number shows that the process is oxidation(or losing of electrons).
-1 to +2, oxidation number is increased. This is an oxidation process.
-
What does the pH of a solution measure?
O A. Color
O B. Volume
O c. Temperature
O D. Acidity
Answer:
D is the correct answer acidity
Explanation:
pH is the logarithmic measurement of the H3O+-concentration in water solutions.
By definition: pH = -log[H3O+]
Example: [H3O+] = 1.0*10-7 mol/L in neutral, pure water (at 25oC), so
pH = -log(H3O+) = -log(1.0*10-7) = 7.0
You have nitrogen gas (N2) at a pressure of 0.5 atm, a volume of 25000 mL, and a temperature of 300 K, how many grams of nitrogen are present?
Answer:
About 7.109g
Explanation:
25000mL is the same as 25 liters.
[tex]PV=nRT \\\\0.5 (25)=n (0.0821) (300) \\\\n\approx 0.508[/tex]
Multiplying this by the molar mass of nitrogen, you get about 7.109 grams of nitrogen. Hope this helps!
The mass of an object is measured in _____. liters meters degrees kilograms
A 10.0 g sample of an unknown liquid is vaporized at 120.0°C and 5.0 atm. The volume of the vapour is found to be 568.0 mL. The liquid is determined to be made up of 84.2% carbon and 15.8% hydrogen. What is the molecular formula for the liquid?
Answer:
C8H16
Explanation:
First thing to do here is to calculate the molar mass of the compound
Mathematically;
molar mass = mass/number of moles
we can calculate the number of moles using the ideal gas equation
Mathematically;
PV = nRT
n = PV/RT
where p is the pressure at 5 atm
V is the volume at 568 ml = 568/1000 = 0.568 L
R is the molar gas constant which is 0.0821
T is the temperature which is 120+ 273 = 393k
Inserting these values into the equation, we have
n = (5 * 0.568)/(0.0821 * 393)
n = 0.088 moles
So the molar mass = 10/0.088
= 114 g/mol
Now let’s go to the percentages
C = 84.2/12 = 7.016666666666667
H = 15.8/1 = 15.8
divide by the smallest
C = 7.016666666666667/7.016666666666667 = 1
H = 15.8/7.016666666666667 = 2 approximately
The empirical formula is CH2
So for the molecular formula, we have;
(12 + 2)n = 114
14n = 114
n = 114/14 = approximately 8
So the molecular formula of the liquid will be (CH2)n = C8H16
a solution of hydrochloric acid contains 1.5 moles of the solute in 2.0 liters of solution. calculate the molarity of this solution
Answer:
0.75 M
Explanation:
Molarity = moles of solute / liters of solution
so;
Molarity = [tex]\frac{1.5 Moles}{2.0 Liters}[/tex]
According to molar concentration, the molarity of this solution is 0.75 molar.
What is molar concentration?Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.
The molar concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molar concentration is calculated by the formula, molar concentration=mass/ molar mass ×1/volume of solution in liters.
In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.Substitution in formula gives, molarity= 1.5/2=0.75 M
Thus, the molarity of this solution is 0.75 molar.
Learn more about molar concentration,here:
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why should we store Phosphorus in water
The reason we should store phosphorous in water is because it will ignite on contact with air
1. If the potassium hydrogen phthalate is not completely dry, how would it affect the reported molar concentration (molarity) of the NaOH solution in Part A? Explain.
The given question is incomplete. The complete question is as follows.
Pure potassiom hydrogen phthalate is used for standardization of the sodium hydroxide solution. Suppose that the potassium hydrogen phthalate is not completely dry. Will the reported molar concentration of the sodium hydroxide solution be too high, too low, or unaffected because of the moistness of the potassium hydrogen phthalate? Explain please.
Explanation:
When potassium hydrogen phthalate is not completely dry then it means there will be some water present in it. According to this, actual potassium hydrogen phthalate is diluted because of the presence of water molecules.
Hence, 1 mole of potassium hydrogen phthalate needs 1 mole of NaOH. And, at the equivalence point according to the concept of moles:
No. of moles of potassium hydrogen phthalate = No. of moles of NaOH
Also, the titration of potassium hydrogen phthalate concentration is less because of the presence of water then the number of moles of NaOH calculated will be less.
Thus, we can conclude that the molar concentration of the sodium hydroxide solution be too low.
ANSWER IT CORRECTLY PLEASE!!
The Osmotic pressure of blood is 7.65 ATM at 310 k. An aqueous solution of glucose is isotonic with blood has the percentage by volume
a.5.41%
b.3.54%
c.4.53%
d.53.4%
Answer:
Explanation:
Pv = n RT
P =7.65, T= 310K, for glucose n = moles= weight/molar mass= weight/180, R is gas constant
7.65* V =W/180 *0.0821 * 310
w/v= 7.65*180/0.0821*310 = 1377/25.45 = 54.10 =5.4%
Does the conductivity increase or decrease?
O It increases at first, then decreases.
O It continuously decreases
O It continuously increases
O lt decreases at first, then increases
Answer:
It continuously decreases.
Explanation:
the thermal motion makes the electrons to collide and disturb the free flow. Thus, conductivity is decreased.
Which of the following contribute(s) to most of the mass of an atom?
O A) Protons and electrons
B) Protons only
C) Protons and neutrons
OD) Neutrons only
Answer:
C) protons and neutrons
Explanation:
im pretty sure it is c
which accurately describes development?
Answer:
changing while growing
Explanation:
Answer: the answer is a
Where do you find the molar mass of an element
Answer:
Mass of a given chemical element or compound divided by the amount of substance.
(g/mol)
Consider the intermediate equations: 3 equations.
C(s) + O2(g) --> CO2(g) Delta H1 = -393.5 kJ
2CO(g) + O2(g) --> 2CO2(g) Delta H2 = -566.0 kJ
2H2O(g) --> 2H2(g) + O2(g) Delta H3 = 483.6 kJ
With the overall reaction:
C(s) + H2O(g) --> CO(g) + H2(g) Delta Hrxn = ?
QUESTION 1:
What must be done to calculate the enthalpy of reaction?
The first must be halved.
The first must be reversed.
The second must be halved.
The second must be reversed.
The third must be halved.
The third must be reversed.
QUESTION 2:
What is the overall enthalpy of reaction?
Delta Hrxn = ____ kJ
Answer:
C. The second equation must be halved
D. The second equation must be reversed
E. The third equation must be halved.
Delta Hrxn= 131.3 kJ
Explanation:
The correct answer is -582 KJ.
What is the enthalpy of reaction?
Enthalpy is the heat content of a system.The enthalpy change of a reaction is roughly equivalent to the amount of energy lost or gained during the reaction.A reaction is favored if the enthalpy of the system decreases over the reaction.What is the overall enthalpy of the reaction?
Equal to the sum of the standard enthalpies of the intermediate reaction steps is called overall enthalpyLearn more about enthalpy below,
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1
Net ionic equations remove spectator ions and shows only the chemical species that are involved in the chemical reaction. Write the net ionic equation for the following acid base reaction.
Molecular Equation: 2 HCl (aq) + Mg(OH)2 (aq) → MgCl2 (aq) + 2 H2O (l)
Complete Ionic: 2 H+ (aq) + 2 Cl– (aq) + Mg2+ (aq) + 2 OH– (aq) → Mg2+ (aq) + 2 Cl– (aq) + 2 H2O (l)
Net Ionic Equation: ______________________________________________________
Answer:
The reaction of an acid and a base is called a neutralization reaction. ... However, in the reaction between HCl(aq) and Mg(OH) 2(aq), additional molecules of HCl and ... First, we will write the chemical equation with the formulas of the reactants ... The chloride ions are the only spectator ions I THINKS
Explanation:
PLSSS HELPPP MEEE WITH THIS QUESTIONNNNN NO GUESSING PLSSSS
Which process is shown in the plant cell below?
A= cell growth
B= cell reproduction
C= metamorphosis
D= photosynthesis
Answer:
B
Explanation:
Well, the cells are going through mitosis, which means that when the divide, they are going to be identical sister cells. Anyways, they are
Name the following 3 structural formulas correctly, in order from left to right
Answer:
1. Methyl propanoate.
2. Propanol.
3. 2–pentyne
Explanation:
1. The functional group in this case is ester. We name ester by naming the group after the functional group (–COO) then followed by the parent compound with the name ending with –oate.
The group after the functional is methyl i.e —CH3.
The parent compound has 3 carbon i.e propane. The functional group replaces the –e in propane with –oate.
Therefore, the name of the compound is:
Methyl propanoate.
2. In this case the functional group is
–OH i.e alcohol.
The compound has 3 carbon i.e propane. The functional group replaces the –e in propane with –ol.
Therefore, the name of the compound is:
Propanol.
3. The triple bond represents the functional group in this case i.e alkyne. We'll give the triple bond the lowest low count by counting from the left. The triple bond is at carbon 2.
The compound has 5 carbon i.e pentyne since it contains triple.
The name of the compound is:
2–pentyne
Photosynthesis produces (4 points)
carbon dioxide and energy
carbon dioxide and oxygen
glucose and oxygen
glucose and carbon dioxide
(I'm pretty positive it's C, but correct me if I'm wrong)
Answer:
Glucose and oxygen is produced during photosyntheis
Explanation:
Carbon dioxide and water are required for photosyntheis producing oxygen and glucose
Answer:
C.Glucose and oxygen
What is the name of Al2(CO3)3 ?
Answer: Aluminum Carbonate
Explanation:
Answer:
Aluminum carbonate.
Explanation:
It is an aluminum salt form of carbonic acid.
A solution has a pH of 8.4. what is the H+ concentration of the solution?
A solution has a pH of 11. What is the H+ concentration of the solution? Is the solution an acid or base?
Your father goes to the store to buy cleaner to remove such deposits from your bathtub. He has a choice between a product containing lemon juice (H+ =10^-2.5M) and one containing vinegar (H+ = 10^ -3.3M) which product would you recommend he purchase and why?
[H+]=3.98x10^-9
[H+]=10^-pH=10^-8.4
[H+]=10^-11, base
[H+]=10^-pH=10^-11
A solution with a pH of more than 7 is basic.
Lemon juice because it is more acidic
pH of lemon juice: 2.5
pH of vinegar: 3.3
Since the pH of lemon juice is lower, it is more acidic and will be more effective at removing the basic deposits.
Give two examples of solutions that you might find or prepare in a kitchen.
Explanation:
solid liquid
solid gas
liquid solid
Respiration occurs in the __________
Respiration occurs in the mitochondria
Answer:
mitochondria
Explanation:
Respiration happens in the cells of plants, animals and humans, mainly inside mitochondria.
What is a chemical solution and what are the names of its components?
Answer:
A chemical solution is defined as a homogeneous mixture of two or more substances. There are two components of chemical solution that include solute and solvent.
Solute is the component that get dissolved in another substance and solvent is the substance that dissolve solute.
For example: carbon dioxide in water. Where carbon-dioxide is solute and water is solvent.
4. Which of these terms describes the process of acid rain wearing away limestone?
Acryptic erosion
B.chemical weathering
C.cryptobiotic weathering
D.chemical erosion
Answer:
B. Chemical weathering
Explanation:
Erosion is the process whereby the soil and rocks are washed away by wind, water, ice or gravity.
Weathering is the process of weakening and breaking down of rocks and minerals either by non-living (abiotic) or living (biotic) factors or by both, such as temperature changes, plants and animals, acids, salts and water, etc.
From the above definitions, it can be seen that acid wearing away limestone is a rock weathering process by a non-living agent, an acid.
Option A is wrong because the process is weathering
Option B is correct because an acid is a chemical and the process involved is weathering
Option C is wrong because an acid is non-living
Option D is wrong because the process involved is weathering
When KCl dissolves in water
Answer:
They form K₂O (Potassium oxide) and HCl (Hydrochloric acid). This is because K and H are positively charged and O and Cl are negatively charged and cations only bond with anions.
What is the total energy required to break all the bonds in 1 mol propanol,
C3H8O?
Answer:
The total energy to break all the bonds in 1 mole of 1-propanol, C₃H₈O, is 4411 kJ/mol
Explanation:
We note that propanol, C₃H₈O is also known as 1-propanol is written as follows;
CH₃CH₂CH₂OH which gives
CH₃-CH₂-CH₂-OH
Hence, the total number of bonds are;
C-H Bonds = 3 + 2 + 2 = 7
C-O Bonds = 1
O-H Bond = 1
C-C Bonds = 2
The bond energies are as follows;
C-H Bonds = 413 kJ/mol
C-O Bonds = 358 kJ/mol
O-H Bond = 468 kJ/mol
C-C Bonds = 347 kJ/mol
Energy required to break the bonds in 1-propanol is therefore;
C-H Bonds = 413 kJ/mol × 7 = 2,891 kJ/mol
C-O Bonds = 358 kJ/mol × 1 = 358 kJ/mol
O-H Bond = 468 kJ/mol × 1 = 468 kJ/mol
C-C Bonds = 347 kJ/mol × 2 = 694 kJ/mol
The total energy to break all the bonds in 1 mole of 1-propanol = 4411 kJ/mol.
What can happen when tectonic plates move a few centimeters?
Answer:
whole continents can move.
The diagram shows Niels Bohr’s model of an atom.
A small green circle labeled Proton is surrounded by 4 concentric circles. The space inside the first concentric circle is labeled N = 1; the space between the first and second circle is labeled N + = 2; between the second and third N = 3, and between the third and fourth N = 4. Oblong gray shapes labeled Electron appear on the second and third concentric circles.
What happens when the electron moves from the first energy level to the second energy level?
Energy is absorbed, and an emission line is produced.
Energy is released, and an emission line is produced.
Energy is absorbed by the atom.
Energy is lost from the atom.
Answer:
Energy is absorbed by the atom.
Explanation:
Why does diamond not conduct electricity
Answer: no free electrons
Explanation: Diamond is very hard due to the strong covalent bonds and rigid tetrahedral 3d arrangement. It does not conduct electricity, as there are no electrons free to move and carry charge through the structure.
this is a multiple choice question. one of the answer from the option given is correct.Could you please help!!My sister needs help but she doesn't trust me '_' why am i even saying this, no one asked
6.What are the main
sources of water pollution?
a) Plastic, paper, metal
b) Snail in water
c) Agriculture, industry and community
C.
i cant explain why..................
