Matter and Their Interactions

A class is doing an experiment to test which solids will dissolve in water. They are testing salt, baking soda, cinnamon, and sugar. How will the students know if each solid dissolves?

• The solid will fall to the bottom of the container.

• The water will become cloudy.

• The water will become bubbly.

• The solid will seem to disappear.

A science class is going to do an experiment to investigate how changing water temperature changes the rate at which salt dissolves in water. What tool will be needed to measure the time it takes for the salt to dissolve?

• stopwatch

• thermometer

• calculator

• hot plate

Jenna put 100 grams of salt into one cup, or 237 mL, of water at room temperature. Only 87 grams of the salt dissolved in the water and the rest stayed on the bottom of the cup. What will happen if she heats the water in the cup?

• the salt will melt

• more salt will dissolve

• less salt will dissolve

• the salt will become a gas

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Danny is trying to figure out how fast sugar crystals can dissolve in water. He has already tested crystals of table sugar by just pouring packets of sugar into a bowl of room-temperature water.

Which should Danny try next if he wants to make the sugar dissolve faster?

• use larger crystals

• cool the water

• stir the water

• all of these

In an experiment, Kyle wants to test how stirring affects the rate at which sugar dissolves into water. He fills three glass beakers with water. Before each test, he will pour sugar into each beaker. In beaker 1, he will not stir the substances. In beaker 2, he will stir the substances slowly. In beaker 3, he will stir the substances quickly. As he stirs, he will use a stopwatch to time how long it takes the sugar to dissolve into the water.

Before he begins the experiment, what should Kyle do?

• find two different size spoons to use for stirring the substances in beakers 2 and 3

• check that beakers 2 and 3 are wider than beaker 1, so water does not spill when stirring

• place beakers 1 and 2 on a hot plate for 5 minutes, so they are warmer than beaker 3

• measure the samples of sugar so the amounts in beakers 1, 2, and 3 are the same

Baking soda is a material that dissolves in water. Amelia wants to test how fast baking soda dissolves at different temperatures. She plans to fill three beakers with water. The water temperature in each beaker will be different. The temperatures will be 10°C, 22°C, and 38°C. Next, she will put baking soda in each beaker. She will then time how long it takes for the baking soda to dissolve in each beaker.

How should Amelia make sure her experiment is controlled?

• The beakers with 10°C and 22°C should be stirred once the baking soda is added.

• The amount of water and baking soda in each beaker should be equal.

• The three beakers should each be tested in a different room of her house.

• The baking soda used in each beaker should have a different particle size.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4