During exothermic reactions:
a. heat is transformed into potential energy
b. kinetic energy is transformed into bond energy
c. potential energy is transformed into bond energy
d. potential energy is transformed into kinetic energy
3 answers
c. potential energy is transformed into bond energy
2. Which of the following are chemical changes?
a. mercury has a density of 13600 kg/m3
b. potassium reacts with water
c. hammer a nail into a piece of wood
d. a rotting apple
e. potassium is a soft metal
f. evaporation of water g. sublimation of dry ice
h. dissolve sugar in water
i. a growing flower
j. hydrogen is a flammable gas
a. mercury has a density of 13600 kg/m3
b. potassium reacts with water
c. hammer a nail into a piece of wood
d. a rotting apple
e. potassium is a soft metal
f. evaporation of water g. sublimation of dry ice
h. dissolve sugar in water
i. a growing flower
j. hydrogen is a flammable gas
The chemical changes among the given options are:
b. potassium reacts with water - This is a chemical change because a chemical reaction occurs between potassium and water, resulting in the formation of potassium hydroxide and hydrogen gas.
d. a rotting apple - This is a chemical change because the organic matter in the apple undergoes decomposition, resulting in the formation of new substances through chemical reactions.
f. evaporation of water - This is a physical change, not a chemical change. Evaporation is the process by which water changes from a liquid to a gas state without undergoing a chemical reaction.
g. sublimation of dry ice - This is a physical change, not a chemical change. Sublimation is the process by which a substance directly changes from a solid to a gas state without going through the liquid phase.
h. dissolve sugar in water - This is a physical change, not a chemical change. Dissolution is a physical process where a solute (sugar) disperses in a solvent (water) without any chemical reaction occurring.
i. a growing flower - This is a biological process involving the growth and development of plant cells, which includes chemical changes occurring within the plant. However, strictly speaking, the growth and development of a flower is a biological process and not solely a chemical change.
j. hydrogen is a flammable gas - The statement is true, but it describes a physical property of hydrogen rather than a chemical change. Flammability is a property of a substance, and it does not necessarily involve a chemical reaction.
Therefore, the correct chemical changes among the options are b. potassium reacts with water and d. a rotting apple.
b. potassium reacts with water - This is a chemical change because a chemical reaction occurs between potassium and water, resulting in the formation of potassium hydroxide and hydrogen gas.
d. a rotting apple - This is a chemical change because the organic matter in the apple undergoes decomposition, resulting in the formation of new substances through chemical reactions.
f. evaporation of water - This is a physical change, not a chemical change. Evaporation is the process by which water changes from a liquid to a gas state without undergoing a chemical reaction.
g. sublimation of dry ice - This is a physical change, not a chemical change. Sublimation is the process by which a substance directly changes from a solid to a gas state without going through the liquid phase.
h. dissolve sugar in water - This is a physical change, not a chemical change. Dissolution is a physical process where a solute (sugar) disperses in a solvent (water) without any chemical reaction occurring.
i. a growing flower - This is a biological process involving the growth and development of plant cells, which includes chemical changes occurring within the plant. However, strictly speaking, the growth and development of a flower is a biological process and not solely a chemical change.
j. hydrogen is a flammable gas - The statement is true, but it describes a physical property of hydrogen rather than a chemical change. Flammability is a property of a substance, and it does not necessarily involve a chemical reaction.
Therefore, the correct chemical changes among the options are b. potassium reacts with water and d. a rotting apple.