Chapter 3 Quiz SolutionsAP Chemistry

Bloom High School

1. A sample of C3H8O that contains 200 molecules contains _____ C atoms.(200 molecules)(3 atoms/molecule)=

600 C atoms

2. When the following equation is balanced, the coefficient of C3H8O is _____.C3H8O(g) + O2(g) CO2(g) + H2O(g)

Organics are harder to balance, especially of things split up, like the O’s!

Try starting with C or H

2C3H8O(g) + O2(g) 3CO2(g) + 8H2O(g)

3. How many grams of H are in 46g of CH4O?

5.8g H

4. S and O react in a combination reaction to produce SO3, an environmental pollutant. In a particular experiment, the reaction of 1.0g S with 1.0g O2 produced 0.80g SO3. The % yield in this experiment is _____. 2S(s) + 3O2(g) 2SO3(g)1. Find Theoretical Yield and Limiting Reagent

(1.0g O2)/(31.9988g O2/mol O2)=0.0312mol O2 used(1.0g S)/(32.065g S/mol S)=0.0312mol S usedBecause the number of moles is the same, there is no limiting

reagent

Theoretical yield = 1.0g + 1.0g = 2.0gExperimental yield = 0.80g

%yield = (Experimental yield)/(Theoretical Yield) x 100%(0.80/2.0)(100) = 40%

5. Al and O2 react in a combination reaction to produce Al2O3. The maximum amount of Al2O3 that can be produced from 2.5g Al and 2.5g O2 is _____.4Al(s) + 3O2(g) 2Al2O3(s)

(2.5g Al)/(26.981538g Al/mol Al)=0.0927mol Al (LR)

(2.5g O2)(mol O2/31.9988g O2)(2mol O/1mol O2)=0.1563mol O

6. When the following equation is balanced, the coefficient of H2O is _____.Ca(s) + H2O(l) Ca(OH)2(aq) + H2(g)

Ca is already balanced. Count O and H on each side.Twice as many on product side as reactant

side.

Ca(s) + 2H2O(l) Ca(OH)2(aq) + H2(g)

7. Al and O2 react in a combination reaction to produce Al2O3. In a particular experiment, the reaction of 2.5g Al and 2.5g O2 produced 3.5g Al2O3. The %yield of the reaction is _____.Theoretical Yield (from #5) = 4.7g Al2O3

Experimental Yield = 3.5g Al2O3

%yield = (Experimental yield)/(Theoretical Yield) x 100%(3.5/4.7)(100) = 74%

8. Fe(CO)5 reacts with PF3 and H2, releasing CO. The reaction of 5.0mol Fe(CO)5, 8.0mol PF3 and 6.0mol H2 will release _____mol CO.Fe(CO)5 + PF3 + H2 Fe(CO)2(PF3)2H2 + CO5.0mol Fe(CO)5 is the limiting reagent (least

moles)Balance first! Start with Fe to see if the

complex is okayFe(CO)5 + 2PF3 + H2 Fe(CO)2(PF3)2H2 +

3CO

(5.0mol Fe(CO)5)(3mol CO/1mol Fe(CO)5)= 15mol CO

9. S and F2 react in a combination reaction to produce SF6. In a particular experiment, the percent yield is 79.0%. This means that in this experiment, a 7.90g sample of F2 yields _____g SF6.

S(s) + 3F2(g) SF6(g)

(7.90g F2)(1mol F2/37.9968064g F2)(1mol SF6/3mol F2)(146.055g SF6/1 mol SF6) = 10.12g SF6

(10.12g SF6)(79.0%) = 7.99g SF6

10. What is the empirical formula of the compound that contains 27.0% S, 13.4% O, and 59.4% Cl by mass?(27.0g S)(1mol S/32.065g S)= 0.842mol S(13.4g O)(1mol O/15.9994g O)= 0.838mol O(59.4g Cl)(1mol Cl/35.453g Cl)= 1.68mol Cl

{0.842, 0.838, 1.68}/0.838 = {1.00, 1.00, 2.00}

S1O1Cl2 SOCl2

11. When the following equation is balanced, the coefficients are _____.NH3(g) + O2(g) NO2(g) + H2O(g)

This problem involves trial and error, mostly because the O splits into two places.

4NH3(g) + 7O2(g) 4NO2(g) + 6H2O(g)

12. AgNO3 and AlCl3 react with each other by exchanging anions. What mass of AgCl is produced when 4.22g of AgNO3 react with 7.73g of AgCl3?3AgNO3(aq) + AlCl3(aq) Al(NO3)3(aq) + 3AgCl(s)

(4.22g AgNO3)/(169.8731g AgNO3/mol AgNO3)=0.0248mol AgNO3 (LR)

(7.73g AlCl3)/(133.34g AlCl3/mol AlCl3)=0.0580mol AlCl3

13. What is the maximum amount of SO3 that can be produced by the reaction of 1.0g S with 1.0g O2?S(s) + O2(g) SO3(g)

Balance first! 2S(s) + 3O2(g) 2SO3(g)

(1.0g S)/(32.065g S/mol S)=0.0312mol S (LR)

(1.0g O2)(mol O2/31.9988g O2)(2mol O/1mol O2)

=0.0625mol O

14. When the following equation is balanced, the coefficient of Al2O3 is _____.Al2O3(s) + C(s) + Cl2(g) AlCl3(s) + CO(g)

Start with AlAl2O3(s) + C(s) + Cl2(g) 2AlCl3(s) + CO(g)

Then ClAl2O3(s) + C(s) + 3Cl2(g) 2AlCl3(s) + CO(g)

Then OAl2O3(s) + C(s) + 3Cl2(g) 2AlCl3(s) + 3CO(g)

Then CAl2O3(s) + 3C(s) + 3Cl2(g) 2AlCl3(s) + 3CO(g)

15. When the following equation is balanced, the coefficient of H2O is _____.K(s) + H2O(l) KOH(aq) + H2(g)

When H2O and OH groups are involved, it’s easier to think of H2O as HOH

K(s) + HOH(l) KOH(aq) + H2(g)

Start with HK(s) + 2HOH(l) KOH(aq) + H2

Then OHK(s) + 2HOH(l) 2KOH(aq) + H2

Then K2K(s) + 2HOH(l) 2KOH(aq) + H2

16. When the following equation is balanced, the coefficient of HCl is _____.CaCO3(s) + HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)

Ca (ok), C (ok), O (ok)Double H and Cl on reactant side only!

CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)

17. When the following equation is balanced, the coefficients are _____.Al(NO3)3 + Na2S Al2S3 + NaNO3

Start with Al2Al(NO3)3 + Na2S Al2S3 + NaNO3

Then NO3

2Al(NO3)3 + Na2S Al2S3 + 6NaNO3

Then Na2Al(NO3)3 + 3Na2S Al2S3 + 6NaNO3

S is already good!2Al(NO3)3 + 3Na2S Al2S3 + 6NaNO3

18. A compound is composed of only C, H, O. The combustion of a 0.519g sample yields 1.24g CO2 and 0.255g H2O. What is the empirical formula of the compound?(1.24g CO2)(1mol CO2/44.0095g CO2)=0.0282mol CO2

(0.255g H2O)(1mol H2O/18.015g H2O)=0.0142mol H2O

0.0282mol C0.0706mol O0.0284mol H

C0.0282H0.0284O0.0706

C1H1O3 (reduced)

19. Predict the product in the combination reaction below.Al(s) + N2(g) _____

Al forms Al+3

N forms N-3

AlN

20. When the following equation is balanced, the coefficient of HNO3 is _____.HNO3(aq) + CaCO3(s) Ca(NO3)2(aq) + CO2(g) +

H2O(l)

Start with H2HNO3(aq) + CaCO3(s) Ca(NO3)2(aq) + CO2(g) +

H2O(l)

Then NO3 (ok), then Ca (ok), then C (ok)…2HNO3(aq) + CaCO3(s) Ca(NO3)2(aq) + CO2(g) +

H2O(l)

21. What is the coefficient of O2 when the following equation is completed and balanced?C4H8O2 + O2 ___ + ___

It is a combustion reaction, therefore:C4H8O2 + O2 CO2 + H2O

Start with CC4H8O2 + O2 4CO2 + H2O

Then HC4H8O2 + O2 4CO2 + 4H2O

Then OC4H8O2 + 5O2 4CO2 + 4H2O

22. Write the balanced equation for the reaction that occurs when CH3OH is burned in air. What is CH3OH’s coefficient?

Any burning in air is a combustion reactionCH3OH + O2 CO2 + H2O

Some organic equations are very tricky. Start with a low number for the first coefficient and balance from there.2CH3OH + O2 CO2 + H2O

Start with C2CH3OH + O2 2CO2 + H2O

Then H2CH3OH + O2 2CO2 + 4H2O

Then O 2CH3OH + 3O2 2CO2 + 4H2O

23. Mg and N2 react in a combination reaction to produce Mg3N2. In a particular experiment, a 9.27g sample of N2 reacts completely. The mass of Mg consumed is _____.3Mg + N2 Mg3N2

24. When the following equation is balanced, the coefficient of H2O is _____.N2O5(g) + H2O(l) HNO3(aq)

Start with NN2O5(g) + H2O(l) 2HNO3(aq)

Then O (ok)Then H (ok)

N2O5(g) + H2O(l) 2HNO3(aq)

25. S and F react in a combination reaction to produce SF6. The maximum amount of SF6 that can be produced from the reaction of 3.5g of S and 4.5g of F2 is _____.S(s) + 3F2(g) SF6(g)

(3.5g S)/(32.065g S/mol S)=0.1092mol S(4.5g F2)(1mol F2/38.00g F2) =0.1184mol F2

(0.1184mol F2)(1mol SF6/3mol F2)(146.055g SF6/1mol SF6) = 5.77g SF6

Calculators!!!Stoichiometry, Unit Convertor, Electron

Configurations, Formula Writer, Equation Balancer, Gas Law Calculations, Empiracal/Molecular Formula Solver

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