7. Write the molecular, total ionic, and net ionic equations for the following r

Question

7. Write the molecular, total ionic, and net ionic equations for the following reactions:

(A) Ca(OH)2(aq) + HC2H3O2(aq)

(B) H3PO4(aq) + CaCl2(aq)

8. Write the balanced equation, then calculate the number of moles and the mass of Mg required to react with   5.00 g of HCl and produce MgCl2 and H2. Ans: 1.67 g Mg

9. H2 is produced by the reaction of 118.5 mL of a 0.8775-M solution of H3PO4 according to the following equation: 2Cr + 2H3PO4 3H2 + 2CrPO4. How many grams of H2 are produced? Ans: .315 g H2

10. Automotive air bags inflate when a sample of sodium azide, NaN3, is very rapidly decomposed.

2NaN3(s) 2Na(s) + 3N2(g)

What mass of sodium azide is required to produce 2.6 ft3 (73.6 L) of nitrogen gas with a density of 1.25 g/L?

Ans: 142 g NaN3

11. Urea, CO(NH2)2, is manufactured on a large scale for use in producing urea-formaldehyde plastics and as a fertilizer. What is the maximum mass of urea that can be manufactured from the CO2 produced by combustion of 1.00 x 104 grams of CO2?

CO2(g) + 2NH3(g) CO(NH2)2(s) + H2O(l)

Ans: 1360 g urea

12. What volume o f 0.750 M hydrochloric acid solution can be prepared from the HCl produced by the reaction of 25.0 g of NaCl with excess sulfuric acid? NaCl(s)   +   H2SO4(l) HCl(g) + NaHSO4(s)

Ans: .570 L

13. A sample of 0.53 g of carbon dioxide was obtained by heating 1.31 g of calcium carbonate. What is the percent yield for this reaction?    CaCO3(s)CaO(s) +   CO2(s)

Ans: 92.0 %

14. Citric acid, C6H8O7, a component of jams, jellies, and fruity soft drinks, is prepared industrially via fermentation of sucrose by the mold Aspergillus niger. The equation representing this reaction is

C12H22O11   +   H2O   +3O2 2C6H8O 7+ 4H2O

What mass of citric acid is produced from the reaction of 150. grams of sucrose if the yield is 92.30%?

Ans: 155 g

15. The phosphorus pentoxide used to produce phosphoric acid for cola soft drinks is prepared by burning phosphorus in oxygen.

(A) What is the limiting reactant when 0.200 mol of P4 and 0.200 mol of O2 react according to P4+5O2 P4O10?

(B) Calculate the percent yield if 10.0 g of P4O10 is isolated from the reaction.

Ans: 88.0 %

16. What is the limiting reactant when 1.50 g of lithium and 1.50 g of nitrogen combine to form lithium nitride, a component of advanced batteries, according to the following unbalanced equation?   Li + N2 Li3N

Ans: Li

17. What is the concentration of NaCl in a solution if titration of 15.00 mL of the solution with 0.2503 MAgNO3 requires 20.22 mL of the AgNO3 solution to reach the end point?

AgNO3(aq) + NaCl(aq) AgCl(s) +NaNO (aq)

Ans: .3374 M

18. In a common medical laboratory determination of the concentration of free chloride ion in blood serum, a serum sample is titrated with a Hg(NO3)2 solution.

2Cl(aq) + Hg(NO3)2(aq) 2NO3(aq) + HgCl2(s)

What is the Cl concentration in a 0.25-mL sample of normal serum that requires 1.46 mL of .000825 MHg(NO3)2(aq) to reach the end point?

Ans: 0.009636 M

Explanation / Answer

(8)

The balanced equation is:

Mg(s) + 2HCl(aq) ---> MgCl2(aq) + H2(g)

Moles of HCl present = Mass/MW = 5/36.46 = 0.137

As per the reaction stoichiometry, moles of Mg required = 0.137/2 = 0.0685

So,

Mass of Mg required = Moles*MW = 0.0685*24.3 = 1.67 g

Hope this helps !

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