A. an endothermic reaction i taking place in a test tube. what would you expect to feel when you touch the outside of the test tube?

b. identify each of the following changes as either exothermic or endothermic.

- burning a candle
- lighting a gas stove
- using an instant cold pack
- running a car's engine

c. on the potential energy diagram below, label the reactants and products. does the diagram shown an endothermic reaction or an exothermic reaction? write one or two sentences explaining your answer.

Explanation:

An endothermic reaction is a type of of chemical reaction in which energy is absorbed from the surrounding. The temperature of the surrounding decreases.

An Exothermic reaction is a type of of chemical reaction in which energy is released into the surrounding. The temperature of the surrounding increases.

a)When an endothermic reaction takes place in test tube the temperature of the surrounding(here the outside wall of the test tube) will decrease which can be felt by touching the outside of the test tube.

b) Burning a candle

,Lighting a gas stove and running a car's engine all are example of exothermic reaction because energy is releases into surroundings. Where as using an instant cold pack is an example endothermic reaction in which energy is absorbed from the surrounding.

c) The diagram is of an exothermic reaction because the energy of the reactants is higher than the energy of the products.The difference in the energies of these two is the energy which was being released on completion of reaction.

a) Endothermic means that the tube will be cold.

b) Candle - exothermic

Lighting a gas stove - exothermic

Using an instant cold pack - endothermic.

Running a car's engine - exothermic.

c) Reactants have higher energy than the products, so it's exothermic cause the difference between energies converted to heat.

area of focus

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.