Question

2. Why is it important to evenly spread the baking soda before heating? efge is imporiont to evenly spread ne lpolens eating is becase What are some safety precautions one must be aware of while performing this experiment? 3. . What is the formula for calculating percent yield? Define each term.

Answer 1

1.) a) molar mass of NaHCO₃=23+1+12+16*3=84 g/mol

b) molar mass of Na₂CO₃ =23*2+12+16*3=106 g/mol

c) molar mass of H₂CO₃=2*1+12+16*3=62 g/mol

2.) Reaction of thermal decomposition of NaHCO₃:

2 NaHCO₃=Na₂CO₃+H₂O+CO₂.

2 mole NaHCO₃ produces 1 mole of Na₂CO₃.

2.765 g NaHCO₃=2.765/84=0.03292 mole.

1.234 g Na₂CO₃=1.234/106=0.01164 mole.

Theoretically, 0.03292 mole NaHCO₃ should produce 0.03292/2 mole=0.01646 mole Na₂CO₃.

So, theoretical yield=0.01646 mole=0.01646*106 g=1.745 g.

% yield=(1.234)*100/1.745 %=70.7 %.

3.) 84*2=168 g NaHCO₃ yields 106 g Na₂CO₃. (Other products are in not solid) So, loss of mass for 168 g NaHCO₃ decomposition is (168-106) g=62 g. Therefore, 0.453 g loss is for( 168/62)*0.453=1.23 g NaHCO₃.

% of NaHCO₃ in mixture of 2.968 g=(1.23/2.968)*100%=41.4%