Question 1

Terephthalic acid, used in the production of polyester fibers and films, is composed of carbon, hydrogen, and oxygen. When 0.6943 g of terephthalic acid was subjected to combustion analysis it produced 1.471 g CO₂ and 0.226 g H₂O. What is its empirical formula? A) C₂H₃O₄ B) C₃H₄O₂ C) C₄H₃O₂ D) C₅H₁₂O₄ E) C₂H₂O

Accepted Answer

To find the empirical formula, we first need to calculate the moles of each element in the compound.
moles of CO2 = 1.471 g / 44.01 g/mol = 0.0334 mol
moles of H2O = 0.226 g / 18.015 g/mol = 0.0126 mol
Using the mole ratio, we divide the moles of each element by the smallest number of moles to get the subscripts for the empirical formula.
C: 0.0334 mol / 0.0126 mol = 2.65 ≈ 3
H: 0.0126 mol / 0.0126 mol = 1
O: 0.0126 mol / 0.0126 mol = 1
Therefore, the empirical formula is C3H1O1, which simplifies to C3H1O or C3H1. This choice is only given in option C.

Question 2

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO₃)₂. A) 107 g B) 90.8 g C) 87.0 g D) 83.4 g E) 62.6 g

Accepted Answer

The answer of Lead (II) nitrate is a poisonous substance...

Question 3

Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H, and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound? A) C₄H₈O₆ B) C₅H₁₀O₅ C) C₅H₁₂O₅ D) C₆H₁₂O₄ E) None of these choices are correct.

Accepted Answer

The answer of Analysis of a carbohydrate showed that it...

Question 4

Balance the following equation for the combustion of benzene: C₆H₆(l) + O₂(g) → H₂O(g) + CO₂(g) A) C₆H₆(l) + 9O₂(g) → 3H₂O(g) + 6CO₂(g) B) C₆H₆(l) + 9O₂(g) → 6H₂O(g) + 6CO₂(g) C) 2C₆H₆(l) + 15O₂(g) → 6H₂O(g) + 12CO₂(g) D) C₆H₆(l) + 15O₂(g) → 3H₂O(g) + 6CO₂(g) E) 2C₆H₆(l) + 9O₂(g) → 6H₂O(g) + 12CO₂(g)

Accepted Answer

The answer of Balance the following equation for the combustion...

Question 5

Gadolinium oxide, a colorless powder which absorbs carbon dioxide from the air, contains 86.76 mass % Gd. Determine its empirical formula. A) Gd₂O₃ B) Gd₃O₂ C) Gd₃O₄ D) Gd₄O₃ E) GdO

Accepted Answer

The answer of Gadolinium oxide, a colorless powder which absorbs...

Question 6

A compound containing chromium and silicon contains 73.52 mass percent chromium. Determine its empirical formula. A) CrSi₃ B) Cr₂Si₃ C) Cr₃Si D) Cr₃Si₂ E) Cr₂S

Accepted Answer

The answer of A compound containing chromium and silicon contains...

Question 7

Copper(II) sulfate pentahydrate, CuSO₄·5H₂O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO₄·5H₂O. A) 249.7 g B) 144.0 g C) 96.00 g D) 80.00 g E) 64.00 g

Accepted Answer

The formula for copper(II) sulfate pentahydrate is CuSO4·5H2O. This means there are 4 oxygen atoms in the sulfate ion (SO4) and 5 water molecules, each containing 1 oxygen atom, for a total of 9 oxygen atoms per formula unit. The molar mass of oxygen is 16.00 g/mol, so the mass of oxygen in 1 mole of CuSO4·5H2O is 9 mol * 16.00 g/mol = 144.0 g.

Question 8

A compound of bromine and fluorine is used to make UF₆, which is an important chemical in processing and reprocessing of nuclear fuel. The compound contains 58.37 mass percent bromine. Determine its empirical formula. A) BrF B) BrF₂ C) Br₂F₃ D) Br₃F E) BrF₃

Accepted Answer

To determine the empirical formula, we need to assume a 100g sample of the compound. This would mean that it contains 58.37g of bromine and 41.63g of fluorine. We can then convert these gram amounts to moles using their respective molar masses: 58.37g Br / 79.904 g/mol Br = 0.730 moles Br 41.63g F / 18.998 g/mol F = 2.19 moles F Next, we divide each mole amount by the smallest mole amount to get the simplest whole number ratio: 0.730 moles Br / 0.730 moles Br = 1 2.19 moles F / 0.730 moles Br = 3 This gives us a ratio of Br:F of 1:3, so the empirical formula would be BrF3. However, none of the answer choices have BrF3, but answer choice E is BrF₃, which simplifies to BrF3, making it the correct answer.

Question 9

Terephthalic acid, used in the production of polyester fibers and films, is composed of carbon, hydrogen, and oxygen. When 0.6943 g of terephthalic acid was subjected to combustion analysis it produced 1.471 g CO₂ and 0.226 g H₂O. If its molar mass is between 158 and 167 g/mol, what is its molecular formula? A) C₄H₆O₇ B) C₆H₈O₅ C) C₇H₁₂O₄ D) C₄H₃O₂ E) C₈H₆O₄

Accepted Answer

The answer of Terephthalic acid, used in the production of...

Question 10

Balance the following equation: UO₂(s) + HF(l) → UF₄(s) + H₂O(l) A) UO₂(s) + 2HF(l) → UF₄(s) + H₂O(l) B) UO₂(s) + 4HF(l) → UF₄(s) + 2H₂O(l) C) UO₂(s) + H₄F₄(l) → UF₄ (s) + H₄O₂(l) D) UO₂(s) + 4HF(l) → UF₄(s) + 4H₂O(l) E) UO₂(s) + 8HF(l) → 2UF₄(s) + 4H₂O(l)

Accepted Answer

In the given equation, U, S, and O are balanced but F and H are not. To balance F and H, there need to be 4 HF molecules on the reactant side and 2 H and 2 F atoms on the product side. This can be achieved by multiplying the entire equation by 4. Thus, the balanced equation is: UO₂(s) + 4HF(l) → UF₄(s) + 2H₂O(l) The only option that matches this balanced equation is choice B.

Question 11

How many protons are there in a molecule of adrenaline (C₉H₁₃NO₃), a neurotransmitter and hormone? A) 22 B) 26 C) 43 D) 98 E) 183

Accepted Answer

Adrenaline, with the molecular formula C9H13NO3, consists of 9 carbon (C) atoms, 13 hydrogen (H) atoms, 1 nitrogen (N) atom, and 3 oxygen (O) atoms. The total number of protons is calculated by adding the atomic numbers of these elements: Carbon (6 protons) x 9 = 54, Hydrogen (1 proton) x 13 = 13, Nitrogen (7 protons) x 1 = 7, and Oxygen (8 protons) x 3 = 24. Adding these together gives 54 + 13 + 7 + 24 = 98 protons.

Question 12

In the combustion analysis of 0.1127 g of glucose (C₆H₁₂O₆), what mass, in grams, of CO₂ would be produced? A) 0.0451 g B) 0.0825 g C) 0.1652 g D) 0.4132 g E) 1.466 g

Accepted Answer

The molecular formula for glucose is C6H12O6. The combustion of glucose can be represented by the balanced chemical equation: C6H12O6 + 6O2 → 6CO2 + 6H2O. This means 1 mole of glucose produces 6 moles of CO2. The molar mass of glucose is approximately 180.16 g/mol, and the molar mass of CO2 is approximately 44.01 g/mol. Given 0.1127 g of glucose, the moles of glucose are 0.1127 g / 180.16 g/mol = 0.0006257 mol. Therefore, the moles of CO2 produced are 6 times this amount, which is 0.0037542 mol. The mass of CO2 produced is 0.0037542 mol * 44.01 g/mol = 0.1652 g.

Question 13

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. Determine its empirical formula. A) HNO B) H₂NO₂ C) HN₆O₁₆ D) HN₁₆O₇ E) H₂NO₃

Accepted Answer

The answer of Hydroxylamine nitrate contains 29.17 mass % N,...

Question 14

Hydroxylamine hydrochloride is a powerful reducing agent which is used as a polymerization catalyst. It contains 5.80 mass % H, 20.16 mass % N, 23.02 mass % O, and 51.02 mass % Cl. What is its empirical formula? A) H₂N₇O₈Cl₁₈ B) H₂N₂O₂Cl C) HN₃O₄Cl₉ D) H₄NOCl E) H₄NOCl₂

Accepted Answer

To determine the empirical formula, we need to find the lowest whole number ratio of the elements in the compound.

We can start by assuming we have 100g of the compound, which means we have:

- 5.80g H
- 20.16g N
- 23.02g O
- 51.02g Cl

Next, we need to convert these masses into moles by dividing by their respective atomic masses:

- 5.80g H / 1.01 g/mol = 5.74 mol H
- 20.16g N / 14.01 g/mol = 1.44 mol N
- 23.02g O / 16.00 g/mol = 1.44 mol O
- 51.02g Cl / 35.45 g/mol = 1.44 mol Cl

Now we need to find the smallest whole number ratio of these moles. We can do this by dividing each mole value by the smallest value, which is 1.44 mol:

- 5.74 mol H / 1.44 mol = 3.99 mol H
- 1.44 mol N / 1.44 mol = 1 mol N
- 1.44 mol O / 1.44 mol = 1 mol O
- 1.44 mol Cl / 1.44 mol = 1 mol Cl

These ratios give us the empirical formula of the compound, which is H4NOCl.

Option D is the only one that has this empirical formula, so it is the best choice.

Question 15

Household sugar, sucrose, has the molecular formula C₁₂H₂₂O₁₁. What is the percent of carbon in sucrose, by mass? A) 26.7% B) 33.3% C) 41.4% D) 42.1% E) 52.8%

Accepted Answer

The answer of Household sugar, sucrose, has the molecular formula...

Question 16

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass O. If its molar mass is between 94 and 98 g/mol, what is its molecular formula? A) NH₂O₅ B) N₂H₄O₄ C) N₃H₃O₃ D) N₄H₈O₂ E) N₂H₂O₄

Accepted Answer

The answer of Hydroxylamine nitrate contains 29.17 mass % N,...

Question 17

The number of hydrogen atoms in 0.050 mol of C₃H₈O₃ is A) 3.0 × 10²² H atoms. B) 1.2 × 10²³ H atoms. C) 2.4 × 10²³ H atoms. D) 4.8 × 10²³ H atoms. E) None of these choices are correct.

Accepted Answer

The answer of The number of hydrogen atoms in 0.050...

Question 18

Balance the following equation: B₂O₃(s) + HF(l) → BF₃(g) + H₂O(l) A) B₂O₃(s) + 6HF(l) → 2BF₃(g) + 3H₂O(l) B) B₂O₃ (s) + H₆F₆(l) → B₂F₆(g) + H₆O₃(l) C) B₂O₃ (s) + 2HF(l) → 2BF₃(g) + H₂O(l) D) B₂O₃ (s) + 3HF(l) → 2BF₃(g) + 3H₂O(l) E) B₂O₃ (s) + 6HF(l) → 2BF₃(g) + 6H₂O(l)

Accepted Answer

The correct balancing of the equation involves 6 HF molecules reacting with the solid to produce 2 BF3 gas molecules and 3 H2O liquid molecules, maintaining the law of conservation of mass.

Question 19

Alkanes are compounds of carbon and hydrogen with the general formula C_nH₂_n₊₂. An alkane component of gasoline has a molar mass of between 125 and 130 g/mol. What is the value of n for this alkane? A) 4 B) 9 C) 10 D) 13 E) 14

Accepted Answer

The answer of Alkanes are compounds of carbon and hydrogen...

Question 20

Determine the percent composition of potassium dichromate, K₂Cr₂O₇. A) 17.5% K, 46.6% Cr, 35.9% O B) 29.8% K, 39.7% Cr, 30.5% O C) 36.5% K, 48.6% Cr, 14.9% O D) 37.2% K, 24.7% Cr, 38.1% O E) None of these choices are correct.

Accepted Answer

The formula for potassium dichromate is K2Cr2O7. To find the percent composition, calculate the molar mass of the compound and then find the mass percentage of each element. The molar mass of K2Cr2O7 is approximately 294.185 g/mol (K=39.1*2, Cr=52.0*2, O=16.0*7). The percent composition is calculated as follows: K: (78.2/294.185)*100 ≈ 26.6%, Cr: (104/294.185)*100 ≈ 35.3%, O: (112/294.185)*100 ≈ 38.1%. None of the choices match these calculations.

Quiz 3: Stoichiometry of Formulas and Equations

Terephthalic acid, used in the production of polyester fibers and films, is composed of carbon, hydrogen, and oxygen. When 0.6943 g of terephthalic acid was subjected to combustion analysis it produced 1.471 g CO₂ and 0.226 g H₂O. What is its empirical formula?

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO₃) ₂.

Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H, and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound?

Balance the following equation for the combustion of benzene: C₆H₆(l) + O₂(g) → H₂O(g) + CO₂(g)

Gadolinium oxide, a colorless powder which absorbs carbon dioxide from the air, contains 86.76 mass % Gd. Determine its empirical formula.

A compound containing chromium and silicon contains 73.52 mass percent chromium. Determine its empirical formula.

Copper(II) sulfate pentahydrate, CuSO₄·5H₂O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO₄·5H₂O.

A compound of bromine and fluorine is used to make UF₆, which is an important chemical in processing and reprocessing of nuclear fuel. The compound contains 58.37 mass percent bromine. Determine its empirical formula.

Balance the following equation: UO₂(s) + HF(l) → UF₄(s) + H₂O(l)

How many protons are there in a molecule of adrenaline (C₉H₁₃NO₃) , a neurotransmitter and hormone?

In the combustion analysis of 0.1127 g of glucose (C₆H₁₂O₆) , what mass, in grams, of CO₂ would be produced?

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. Determine its empirical formula.

Hydroxylamine hydrochloride is a powerful reducing agent which is used as a polymerization catalyst. It contains 5.80 mass % H, 20.16 mass % N, 23.02 mass % O, and 51.02 mass % Cl. What is its empirical formula?

Household sugar, sucrose, has the molecular formula C₁₂H₂₂O₁₁. What is the percent of carbon in sucrose, by mass?

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass O. If its molar mass is between 94 and 98 g/mol, what is its molecular formula?

The number of hydrogen atoms in 0.050 mol of C₃H₈O₃ is

Balance the following equation: B₂O₃(s) + HF(l) → BF₃(g) + H₂O(l)

Alkanes are compounds of carbon and hydrogen with the general formula C_nH₂_n₊₂. An alkane component of gasoline has a molar mass of between 125 and 130 g/mol. What is the value of n for this alkane?

Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

Quiz 3: Stoichiometry of Formulas and Equations

Terephthalic acid, used in the production of polyester fibers and films, is composed of carbon, hydrogen, and oxygen. When 0.6943 g of terephthalic acid was subjected to combustion analysis it produced 1.471 g CO2 and 0.226 g H2O. What is its empirical formula?

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO3) 2.

Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H, and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound?

Balance the following equation for the combustion of benzene: C6H6(l) + O2(g) → H2O(g) + CO2(g)

Gadolinium oxide, a colorless powder which absorbs carbon dioxide from the air, contains 86.76 mass % Gd. Determine its empirical formula.

A compound containing chromium and silicon contains 73.52 mass percent chromium. Determine its empirical formula.

Copper(II) sulfate pentahydrate, CuSO4·5H2O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO4·5H2O.

A compound of bromine and fluorine is used to make UF6, which is an important chemical in processing and reprocessing of nuclear fuel. The compound contains 58.37 mass percent bromine. Determine its empirical formula.

Balance the following equation: UO2(s) + HF(l) → UF4(s) + H2O(l)

How many protons are there in a molecule of adrenaline (C9H13NO3) , a neurotransmitter and hormone?

In the combustion analysis of 0.1127 g of glucose (C6H12O6) , what mass, in grams, of CO2 would be produced?