Question 1

Household sugar, sucrose, has the molecular formula C₁₂H₂₂O₁₁. What is the % 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 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 molar mass of Pb(NO3)2 is (207.2 g/mol) + 2(14.01 g/mol) + 6(16.00 g/mol) = 331.2 g/mol.
Since we have 139 g of Pb(NO3)2, we can use the following calculation:
(Lead mass/molar mass of Pb(NO3)2) = (mass of Pb(NO3)2/ molar mass of Pb(NO3)2)
Lead mass = (mass of Pb(NO3)2/ molar mass of Pb(NO3)2) × molar mass of Pb = (139 g/331.2 g/mol) × 207.2 g/mol = 87.0 g
Therefore, the mass of lead in 139 g of Pb(NO3)2 is 87.0 g. The answer is C.

Question 3

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 4

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 5

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 6

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 7

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 determine the number of moles of each element present in the compound.

Number of moles of C = (mass of CO2 produced)/(molar mass of CO2) 
= 1.471 g / 44.01 g/mol 
= 0.0334 mol

Number of moles of H = (mass of H2O produced)/(molar mass of H2O) 
= 0.226 g / 18.02 g/mol 
= 0.0126 mol

Number of moles of O = (number of moles of CO2 + number of moles of H2O) - (number of moles of terephthalic acid) 
= (0.0334 mol + 0.0126 mol) - (0.6943 g / 166.13 g/mol) 
= 0.0126 mol

Now, we need to find the simplest whole-number ratio of C, H, and O using these molar amounts.

C: 0.0334 mol / 0.0126 mol = 2.65 
H: 0.0126 mol / 0.0126 mol = 1.00 
O: 0.0126 mol / 0.0126 mol = 1.00

The empirical formula is therefore C2.65H1O1 or, simplified to whole numbers, C13H5O2. The closest answer choice is C, which matches this formula.

Question 8

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 9

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

The answer of A compound of bromine and fluorine is...

Question 10

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

Accepted Answer

The answer of Balance the following equation: B₂O₃(s) + HF(l)...

Question 11

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 first need to find the molar ratios of each element. We can do this by assuming a 100 g sample of the compound, which would mean we have: H: 5.80 g N: 20.16 g O: 23.02 g Cl: 51.02 g Next, we convert these masses into moles by dividing by their respective molar masses (1.008, 14.007, 15.999, 35.453 g/mol): H: 5.76 mol N: 1.44 mol O: 1.44 mol Cl: 1.44 mol We then divide each mole value by the smallest mole value (1.44 mol) to get the mole ratios: H: 4 N: 1 O: 1 Cl: 1 This gives us an empirical formula of H4NClO. However, we should simplify this by dividing each subscript by 4: H1NCl0.25O0.25 Since we want integer values for our subscripts, we can multiply everything by 4 to get: H4NClO Therefore, the empirical formula is D) H₄NOCl.

Question 12

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 is correct.

Accepted Answer

The answer of Determine the percent composition of potassium dichromate,...

Question 13

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

Accepted Answer

The answer of Balance the following equation: UO₂(s) + HF(l)...

Question 14

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 is correct.

Accepted Answer

Each molecule of C3H8O3 contains 8 hydrogen atoms. Therefore, 0.050 mol of C3H8O3 contains 0.050 mol * 8 = 0.40 mol of H atoms. Using Avogadro's number (6.022 * 10^23 atoms/mol), the number of hydrogen atoms is 0.40 mol * 6.022 * 10^23 atoms/mol = 2.4 * 10^23 H atoms.

Question 15

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 16

Calculate the mass in grams of 8.35 * 10²² molecules of CBr₄. A) 0.0217 g B) 0.139 g C) 7.21 g D) 12.7 g E) 46.0 g

Accepted Answer

The answer of Calculate the mass in grams of 8.35...

Question 17

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 18

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 is correct.

Accepted Answer

The empirical formula based on the given percentages is C₅H₁₀O₅, which matches the molecular mass range of 140-160 amu.

Question 19

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 20

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...

Quiz 3: Stoichiometry of Formulas and Equations

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

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.

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?

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?

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

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?

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: B₂O₃(s) + HF(l) $\rightarrow$ BF₃(g) + H₂O(l)

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?

Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

Balance the following equation: UO₂(s) + HF(l) $\rightarrow$ UF₄(s) + H₂O(l)

The number of hydrogen atoms in 0.050 mol of C₃H₈O₃ is

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

Calculate the mass in grams of 8.35 * 10²² molecules of CBr₄.

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?

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?

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

Quiz 3: Stoichiometry of Formulas and Equations

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

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.

Alkanes are compounds of carbon and hydrogen with the general formula CnH2n+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?

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?