4.7: Unit 4 Practice Problems
- Page ID
- 260643
Problem 1.
Balance the following equations:
- PCl5(s)+H2O(l)→POCl3(l)+HCl(aq)
- Cu(s)+HNO3(aq)→Cu(NO3)2(aq)+H2O(l)+NO(g)
- H2(g)+I2(s)→HI(s)
- Fe(s)+O2(g)→Fe2O3(s)
- Na(s)+H2O(l)→NaOH(aq)+H2(g)
- (NH4)2Cr2O7(s)→Cr2O3(s)+N2(g)+H2O(g)
- Answer 1
-
PCl5(s)+H2O(l)→POCl3(l)+2HCl
- Answer 2
-
3Cu(s)+8HNO3(aq)→3Cu(NO3)2(aq)+4H2O(l)+2NO(g)
- Answer 3
-
H2(g)+I2(s)→2HI(s)
- Answer 4
-
4Fe(s)+3O2(g)→2Fe2O3(s)
- Answer 5
-
2Na(s)+2H2O(l)→2NaOH(aq)+H2(g)
- Answer 6
-
(NH4)2Cr2O7(s)→Cr2O3(s)+N2(g)+4H2O(g)
Question 2.
Write the balanced chemical equation for the combustion of gaseous butane, C4H10.
Answer
-
2C4H10(g)+13O2(g)→8CO2(g)+10H2O(g)
Question 3.
What is the mass of 0.54mole of CO2?
- Answer
- \[\mathrm{0.54\: \cancel{mole} \times \dfrac{44\: g}{1\:\cancel{mole}}=24\: g}\]
Question 4.
230 grams of O is how many moles of O?
- Answer
- \[\mathrm{230\: \cancel{g} \times \dfrac{1\: mole}{16\:\cancel{g}}=14\: mole O}\]
Question 5.
What is the mass of 1.00 mole of magnesium nitrate?
- Answer
- The formula for magnesium nitrate is Mg(NO3)2 mass = (1 x 24.31) + (2 x 14.01) + (6 x 16.00) = 148 g Mg(NO3)2
Question 6.
How many atoms are on 1.76 moles of phosphorus?
- Answer
- \[\mathrm{1.76\: \cancel{mole} \times \dfrac{6.02e23\: atoms}{1\:\cancel{mole}}=1.06e24\: atoms}\] 1.06x1024atoms
Question 7.
What is the mass of 3.57x1024molecules of CaS?
- Answer
Question 8.
Automotive air bags inflate when a sample of sodium azide, NaN3, is very rapidly decomposed.
2NaN3(s)→2Na(s)+3N2(g)
If this reaction begins with only 1.46 moles of NaN3, how many moles of nitrogen gas, N2, will be produced?
- Answer
Question 9.
What mass of silver oxide, Ag2O, is required to produce 25.0 g of silver sulfadiazine, AgC10H9N4SO2, from the reaction of silver oxide and sulfadiazine?
2C10H10N4SO2+Ag2O→2AgC10H9N4SO2+H2O
- Answer
-
= 8.11 g Ag2O
Question 10.
Identify the energy graphs A and B as being for an endothermic or exothermic reaction.
A.
B.
- Answer
- A. exothermic B. endothermic