Stoichiometry

Question 1

What is the volume of 3 moles of O₂ at standard temperature and pressure (STP)?

Answer 1

67.2 l = 3 x22.4 l

Question 2

In the reaction H₂SO₄ + HI –> I₂ + SO₂ + H₂O what is H₂SO₄?

Answer 2

oxidizing agent which loses electrons

Question 3

Balance the following reaction C₆H₁₄ + O₂ –> CO₂ + H₂O

Answer 3

2 C₆H₁₄ + 19 O₂ –> 12 CO₂ + 14 H₂O

Question 4

True or false: An oxiidzation number is the charge that an atom appears to have when the electrons in each bond are assigned to the more elctronegative of the two atoms involved in the bond.

Answer 4

true

Question 5

What is the empirical formula of acetic acid, CH₃COOH?

Answer 5

CH₂O

Question 6

In which of the following compounds does Cl have an oxidization number of +7?

a. NaClO₂
b. Al(ClO₄)₃
c. Ca(ClO₃)₂
d. LiClO₃
e. none

Answer 6

b. Al(ClO₄)₃

Question 7

What is thr formula mass of CO₂?

Answer 7

44 amu

Question 8

What is the product of heating cadium metal and powdered sulfur?

Answer 8

CdS

Question 9

Balance the following reaction Cl₂(g) + NaI(aq) –> I₂(s) + NaCl(aq)

Answer 9

Cl₂(g) + 2 NaI(aq) –> I₂(s) + 2 NaCl(aq)

Question 10

Which is the strongest reducing agent in the redox reaction, FeCl₃(aq) + NaI(aq) –> I₂(s) + FeCl₂(aq) + NaCl(aq)

Answer 10

NaI

Question 11

If 14.5 moles of N₂(g) are mixed with 34 moles of H₂(g) in the following reaction N₂(g) + 3 H₂(g) –> 2NH₃(g) and the reaction yields 18 moles of NH₃(g), how many moles of N₂(g) remain.

Answer 11

5.5 moles on N₂(g)

Question 12

True or false: CaCO3 –> CaO + CO2 is a decomposition/redox reaction.

Answer 12

false, not redox since no gain or loss of electrons

Question 13

How many gram of H₂O can be formed in a reaction between 10 grams of oxygen and 1 grams of hydrogen

Answer 13

9 grams of H₂O since 0.5 O₂ + H₂ –> H₂O

stoichiometric ratio: 0.5 O₂ : 1 H₂ : 1 H₂0

mass ratio: 16 O₂ : 2 H₂ : 18 H₂O

Question 14

How many grams of Ba²⁺ ions are in an aquesous solution of BaCl₂ that contains 6.8 x 10²² Cl ions?

Answer 14

7.8 g because have 0.113 moles of Cl ions and 0.0565 moles of Ba ions

Question 15

What is the oxidation number of Br in NaBrO₃?

Answer 15

5

Question 16

True or false: 2 H₂O₂(s) –> 2 H₂O(l) + O₂(g) is decompostion non-redox reaction.

Answer 16

False. decomposition redox reation

Question 17

Calculate the number of O₂ molecules if a 15.0 l cylinder is filled with O₂ at STP.

Answer 17

4.03 x 10²³ = 15.0 / 22.4 x 6.022 x 10²³

Question 18

True or false: In a redox reaction balanced by the oxidization number method by determining the electrons lost by substance oxidized and the electrons gained by substance reduced.

Answer 18

true

Question 19

Write equation which represents the oxidation of Co²⁺.

Answer 19

Co²⁺ –> Co³⁺ + e^-

Question 20

How many moles of phosphorus trichloride are required to produce 365 grams of HCl when the reaction yields 75%. PCl₃(g) + 3 NH₃(g) –> P(NH₂)₃ + 3 HCl(g)

Answer 20

365 g HCl = 10 moles HCl

since yield is 75% then 10 moles/0.75 = 13.3 moles

stoichiometric ratio: 1 PCl₃ : 3 HCl

13.3 moles/3 = 4.17 moles of PCl₃

Question 21

What is oxidation number of liquid bromine in elemental state?

Answer 21

0, all elements in fee state ave oxidization number of 0

Question 22

In the unbalanced reaction C₃H₈(g) + O₂(g) –> CO₂(g) + H₂O(g) if 2.6 of propane is burned what volume of H₂O is produced?

Answer 22

Stoichiometric ratio: 1 C₃H₈ : 4 H₂O

4 x 2.6 l = 10.4 l

Question 23

When aluminum reacts with ferric oxide (Fe₂O₃), a displacement reaction yields two products with one being metallic iron, what is the sum of coefficints of the products of the balanced reaction?

Answer 23

3

Fe₂O₃ + Al –> 2 Fe + AlO₃

Question 24

Which substance is reduced in the following redox reaction?

HgCl₂(aq) + Sn²⁺(aq) –> Sn⁴⁺(aq) + Hg₂Cl₂(s) + Cl^-(aq)

Answer 24

HgCl₂(aq)

Question 25

What is coefficient of P in the balanced equation

P(s) + O₂(g) –> P₂O₅(s)

Answer 25

4

Question 26

True or false: In abasic solution, the followig are guidelines for balancing a redox reaction by half reaction method.

1. Add the two half-ractions together and cancel dentical species on each side of the equation
2. Multiply each half-reaction by a whole number of electrons lost by the substance oxidized is equal to the electrons gained by the substance reduced
3. Write balanced half-reaction for the substance oxidized and the substance reduced.

Answer 26

true

Question 27

What is the molecular formula of galactose, if the empirical formula is CH₂O and the molar mass is 180 g/mole?

Answer 27

C₆H₁₂O₆

Question 28

How many formula units of lithium iodide (LiI) have mass equal to 6.45g if LiI = 133.85 g/mole

Answer 28

~2.9 x 10²²

Question 29

What are the possible products of N₂ and O₂?

Answer 29

NO, NO₂, N₂O

Question 30

What is coefficient of O in the balanced equation

P(s) + O2(g) –> P2O3(s)

Answer 30

3

Question 31

Which substance is the weakest reducing agent given the spontaneous redox reaction?

Mg(s) + Sn²⁺(aq) –> Mg²⁺(aq) + Sn(s)

Answer 31

Sn(s)