Question

Physical and Chemical Changes
State which of the following changes are physical or chemical. Explain your answer.

a. Baking a pandesal
b. Melting of ice
c. Chewing a cake
d. Burning a log
e. Evaporating alcohol

Answer 1

a.) Baking a pandesal is a chemical process.By consuming sugar,yeast converts to C02 which helps the dough rise which is an irreversible process so it is a chemical change.

b.) Melting of ice is a physical change because we can reverse the process by changing external conditions.

c.) Chewing a cake is a chemical change because the saliva reacts with the cake and it changes chemically which cannot be reversed.

d.) Burning of a log is a chemical change because wood in presence of heat and oxygen gets converted to C02,water vapour and ash and this process is irreversible.

e.) Evaporation of alcohol is a physical change because only phase changes which can be reversed by changing temperature and pressure.