Chemistry Final Answer Key 2018
1. Potassium permanganate and glycerin react explosively according to the following equation: 14 KMnO4 + 4 C3H5(OH)3 → 7 K2CO3 + 7 Mn2O3 + 16 H2O + 5CO2
a) How many moles of carbon dioxide can be produced from 4.44 mol of KMnO4?
1.59 mol CO2
b) If 5.21 g of H2O are produced, how many moles of glycerin, C3H5((OH)3 , were used? 0.0723 mol C3H5((OH)3
c) If 3.39 mol of potassium carbonate are made, how many grams of manganese(III) oxide are also made? 535 g Mn2O3
d) How many grams of glycerin will be needed to react with 50.0 g KMnO4? How many grams of CO2 will be produced in the same reaction? 8.33 g C3H5(OH)3 ; 4.97 g CO2
2. A reaction such as the one shown here is often used to demonstrate a single replacement reaction.
3CuSO4(aq) + 2 Fe(s) → 3 Cu(s) + Fe2(SO4)3(aq)
If you place 0.092 mol of iron filings in a solution containing 0.158 mol of CuSO4, what is the limiting reactant? How many moles of Cu will be formed? Fe is limiting, 0.138 mol Cu
3. In the commercial production of the element arsenic(III) oxide is heated with carbon, which reduces the oxide to the metal according to the following equation:
2As2O3 + 3C → 3CO2 + 4 As
a) If 8.87 g of As2O3 is used in the reaction and 5.33 g of As is produced, what is the percentage yield? 79.3% yield
b) If 67 g of carbon is used up in a different reaction and 425 g of As is produced, calculate the percentage yield of this reaction. 76% yield
4. The reaction N2(g) + 3H2(g) → 2 NH3(g) is used to produce ammonia commercially. If 5.6 L of N2 are used in the reaction, how many liters of NH3 are produced? 11.2 L NH3
5. Explain on the molecular level why liquids have a definite volume but no definite shape.
According to molecular theory, the molecules of a liquid are in motion and are able to slide over one another making them flow, but they are much closer together than a gas’ particles so they do have a definite volume.
6. What determines the boiling point of a substance? The boiling point is the temperature where the vapor pressure of the liquid is equal to the atmospheric pressure of the air around it.
7. What phase transition occurs as a gas becomes a solid? It goes through deposition.
8. For the diagram above:
a. In what state is point A? solid
b. What are the pressure and temperature for the triple point? .08 atm and 150 K
c. If a liquid at 1 atm and 300 K is cooled to 150 K, what transition does it go through? It goes through the process of freezing.
9. Using the chart above, calculate the amount of heat transfer as 200 g Benzene is heated from 0° C to 80° C. 51536 J do not do
10. How much heat is released as 50 g water cools from 100° C to 50° C? 10450 J
11. Explain how the specific heat of water affects the weather at the shore. The ocean water takes longer to warm up than the air and the land. So onshore breezes keep the shore cooler than the land further in from the coast.
12. A child receives a balloon filled with 2.30 L of...