CHEMISTRY 121
WORKSHEET CH #9&10
FEBRUARY 10, 2016
ΔE=q+w,
1. A student combines 5.66 grams of zinc with 9.33 g of hydrochloric acid.
a. Write a balanced equation
b. Determine the mass of hydrogen produced
c. Which reactant is in excess?
d. What is the percent yield if 1.44 g of hydrogen is produced?
2. Alcohol component of gasoline burns by a combustion equation. Assume the formula is C2H6O for this
alcohol and 833 kJ is released in the process.
a. Write a balanced thermochemical equation
b. How much energy is released when 5.66 g of water is produced?
3. A system releases 125 J of heat, and 104 kj of work is done on the system. Calculate ΔE.
4. If 125 j of heat energy is applied to a block of silver weighing 29.3 g, by how much will the temperature
increase in degrees Celsius? The specific heat of silver is 0.24 j/g-°C.
5. Given the following data:
S(s) + 3/2 O2 (g)
SO3(g)
2SO2(g) + O2(g)
2SO3(g)
Calculate ΔH for the reaction S(s) +O2(g)
2SO3(g)