If 20.00 moles of calcium reacted, how many grams of calcium oxide are produced?

1 Answer
Jun 7, 2017

Answer:

#1122" g CaO"#

Explanation:

First you need to create the skeletal equation for the reaction. Since calcium oxide (CaO) is produced, oxygen (#O_2)# is required.

Skeletal equation: #Ca + O_2 -> CaO#

Balance the equation based on the law of conservation of mass. Since there are two oxygen atoms on the left, a #2# coefficient is required:
#" "Ca + O_2 -> 2CaO#

Now you need to have #2# calcium molecules on the left to balance:

#" "2Ca + O_2 -> 2CaO#

This equation is balanced. The equation says that for every two moles of calcium, there are two moles of calcium oxide produced.

The molar mass of CaO #= 40.078 + 15.999 = (56.077" g CaO")/(1 "mol CaO") #

#20.00 " mol Ca" xx (2" mol CaO")/(2" mol Ca") xx (56.077" g CaO")/(1 " mol CaO") #

#= 1121.54 " g CaO"#

If you take into consideration significant figures (SF), the smallest number of SF is 4. This would mean your answer should be #1122 " g CaO"#