1.5 Chemical Reactions

Multiple Choice

What is an example of a chemical change?

• Tearing paper

• Dissolving salt in water

• Melting ice

• Burning wood

Multiple Choice

Does this image represent a chemical or a physical change?

• Chemical change

• Physical change

Multiple Choice

Does this image represent a chemical or physical change?

• Chemical change

• Physical change

Multiple Choice

A clear liquid from a flask is poured into another clear liquid in a beaker. Which of the following results of this procedure would indicate a new substance was formed?

• The level of the substance in the beaker is higher after the other liquid is added.
• A yellow solid forms and then settles to the bottom of the beaker.
• Small white crystals are left behind in the flask that held the first liquid.
• The mass of the combined liquids is greater than either original liquid.

Multiple Choice

What are the reactants of this equation?

• $$N_2+H_2$$

• $$2NH_3$$

Multiple Choice

$$2Al^{ }\ +\left(SO_4^{ }\right)\ \rightarrow\ Al_2\left(SO_4\right)_3$$  

What are the products of this equation?

• $$2Al^{ }\ +\left(SO_4^{ }\right)$$  

• $$Al_2\left(SO_4\right)_3$$  

Multiple Choice

What are the PRODUCTS of this equation?

• $$CH_4\ +\ 2O_2$$

• $$CO_2+\ 2H_2O$$

Multiple Choice

$$2Al^{ }\ +\left(SO_4^{ }\right)\ \rightarrow\ Al_2\left(SO_4\right)_3$$  

What are the REACTANTS of this equation?

• $$2Al^{ }\ +\left(SO_4^{ }\right)$$  

• $$Al_2\left(SO_4\right)_3$$  

Multiple Choice

Mrs. Andrews did a science demonstration with dry ice. First, she placed some dry ice inside of a balloon. Then she tied off the balloon and placed it on a triple beam balance. The balance showed that the combined mass of the balloon and dry ice was 22 grams. While the balloon sat on the balance, it began to expand. As the dry ice sublimed, or changed from a solid into a gas, the gas filled the balloon. When the dry ice had sublimated completely, how much mass was sitting on the balance and why?

• More than 22 grams because the balloon inflated, so its mass increased.

• Exactly 22 grams because mass cannot be created or destroyed by ordinary physical changes.

• Less than 22 grams because a gas weighs less than a solid.

• Less than 22 grams because warm things weigh less than cold ones.

Multiple Choice

Joanna fills a glass with 30 grams of water. She pours the water into a tray to make ice cubes.

The tray has room to make 6 ice cubes. Joanna is careful not to spill any of the water as she pours it into the tray with an equal amount in each cube of the tray.

How much mass should each of the ice cubes have?

• 30 grams

• 10 grams

• 0 grams

• 5 grams

Multiple Choice

Jackie and Josh wanted to do an experiment to demonstrate the Law of Conservation of Mass. To do this, they measured the mass of baking soda and vinegar (reactants) and received a mass of 35g. Then, they mixed the two substances and after the reaction, the mass was measured at 33g. What is the possible explanation as to why the mass was not the same before and after the reaction?

• Mass was destroyed in the reaction.

• They did not measure correctly.

• The students did not include an instrument to capture the gas produced in the reaction.

• These two substances do not react so nothing would have happened.