1-Why is it important to leave the lid askew when heating the empty crucible at the start of the procedure in this experiment?

A.To allow water to be driven off and escape from the crucible so it doesn’t contribute to the mass of the crucible

B.To allow you to obseve any changes inside the crucible, which may be important for your results and discussions when you write up your lab report sheets

C.To allow any steam to condense on the underside of the lid – the lid must be at an angle to effectively capture the condensing steam

D.To prevent pressure from building up inside and having the crucible explode

2-Why is it important to heat & cool your sample in the crucible at least twice in this experiment?

A.So that you can average several results and statistically analse your data

B.Because the reaction proceeds step-wise, and you need at least two steps to ensure the reaction goes to completion

C.So that you can be sure you have reached a constant mass, and there is no further change

D.To reduce the mass of your sample to a value comparable to the value obtained by other students in the lab – this increases the confidence in your results

3-The stoichiometric ration of sodium bicarbonate consumed to carbon dioxide produced is:

A.unknown – to be determined

B.3:2

C.1:1

D.1:2

E.2:1

4-the ratio of sodium bicarbonate to potassium chloride in this experiment is:

A.1:1

B.1:2

C.2:1

D.3:2

E.unknown – to be determined

5-In this experiment, the production of CO2 and H2O indicates:

A.Combustion of sodium bicarbonate

B.Combustion of organic residues

C.Decomposition of sodium bicarbonate

D.Decomposition and evaporation of all of the sample components. 

E.All of the above