Evidence of Chemical Reactions

Front

Which of the following examples shows that a chemical reaction has occurred? A rock breaks into smaller pieces when it is struck with a hammer., Rust forms on a hammer that has been left outside too long., A cup of water turns pink when a few drops of red food coloring are added., A solid is formed when heat is removed from a sample of water.

Back

Rust forms on a hammer that has been left outside too long.

Front

Why do bubbles form around a potato in hydrogen peroxide?

Back

could show that a gas is forming

Front

In which experiment are new substances being formed?

Back

Experiment 1

Front

Hydrogen peroxide breaks down to form water and oxygen gas. Which observation is evidence that a chemical reaction has occurred?

Back

The temperature of the solution increases.

Front

A clear liquid from a flask is poured into another clear liquid in a beaker. Which result indicates a new substance was formed?

Back

A yellow solid forms and then settles to the bottom of the beaker.

Front

Which of the following is an example that includes evidence of a chemical reaction?

Back

Sugar that is burned gives off an odor and turns brown and then black.

Front

In a container, a solid consisting of clear crystals is combined with a blue liquid and the following observations are obtained. How many of the listed observations indicate a new substance was formed?

Back

3

Front

Evidence of a chemical reaction is anything that shows -

Back

a new substance has formed

Front

What is a precipitate?

Back

a solid that forms when two liquids are mixed

Front

If reaction starts with 20g of reactants, it should produce how many grams of products?

Back

a total of 20g of products