im trying to find the mass of CO2 evolved in each beaker. The answer the teacher said is suppose to be 1.78 for beaker 1 and 1.77 for beaker 2.

im trying to find the mass of CO2 evolved in each beaker. The answer the teacher said is suppose to be 1.78 for beaker 1 and 1.77 for beaker 2. In the instructions it says to subtract the final mass from the initial mass which i did but i get a different answer. The initial mass for beaker one is 124.000g and the final mass is 122.822g. For beaker 2 the initial is 124.007 and the final is 122.916?