Introduction to Chemistry

Which of the following is true about the principle of the conservation of mass?

• The mass of the products is never equal to the mass of the reactants.

• The mass of the products is less than the mass of the reactants.

• The mass of the products is equal to the mass of the reactants.

• The mass of the products is greater than the mass of the reactants

Tags

NGSS.MS-PS1-5

Jay had two clear liquids in bottles. The mass of one liquid was 10.0 grams and the other was 7.0 grams. When he mixed them, a yellow solid formed and settled to the bottom of the bottle. He predicted that the liquid plus the solid would have more mass, so he put the bottle on a scale. The mass was 17.0 grams. Why did the mass not change?

• Because it is a mixture and mass doesn't change.

• His scale is broken.

• Do to the Law of conservation of mass, matter cannot be created nor destroyed so the mass is the same as the reactant and the product.

• He forgot to tare his bottle and the scale had the mass of the bottle added in.

Tags

NGSS.MS-PS1-5

Describe three pieces of evidence you could look for to determine whether a chemical reaction occurred.

• Formation of a gas

• Formation of a precipitate

• Temperature change

• Color change

• property change

Tags

NGSS.MS-PS1-2

Does this model represent a chemical reaction.

Choose all the answers that will create a CER.

• This model shows a chemical reaction because all of the atoms are rearranged to form something new.

• The model shows that 2 Mg plus 2 O formed a new substance could 2MgO.

• Since, the product is different then the reactant, I know a chemical reaction occurred.

• I know this is correct by looking at the model.

Tags

NGSS.MS-PS1-2

According to the model, how does the total mass compare to the total mass after two weeks? Write an explanation to support your answer.

• The mass will stay the same because matter is neither created or destroyed the atoms are just rearranged to form something new.

• The mass will change because it is in an open system.

• The mass will decrease because after time the oxygen will float away.

• The mass will stay the same because it is the same thing.

Tags

NGSS.MS-PS1-5

Your teacher gives you a clear liquid, a white powder, and a red powder. Design an experiment to find out which two substances when mixed together will produce a chemical reaction. Pick all the correct answers.

• Mix the 1/2 of the red powder with the 1/2 of the clear liquid and record what happens.

• Mix 1/2 of the white powder with the other 1/2 of the clear liquid record what happens.

• Mix the substances all together and see what happens.

• Mix the other half of the red powder with the white powder and record what has happened.

• Create a data table to record your observations and analyze your data.

Tags

NGSS.MS-PS1-2

Which of the following is a chemical reaction?

• New atoms are formed when substances are mixed together

• A solid material melts and becomes a liquid

• Atoms of the reactants rearrange to form a new substance

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student dissolves 3 gram of sugar in 10 grams of water. She then determines the mass of the solution. What is the mass of the dissolved sugar and water?

• 13 grams because the substance is a mixture and the molecules are floating next to each other.

• 13 grams because a chemical reaction occurred making a new substance.

• Less then 13 grams because the water absorbed the sugar.

• More than 13 grams because the sugar absorbed the water.

Tags

NGSS.MS-PS1-5

Which statement is always true about conservation of matter?

• If a gas forms, the mass of a system decreases.

• The mass of a system does not change during a chemical reaction.

• If a solid forms, the mass of a system increases.

• The mass of a system changes when a substance changes from liquid to gas, but it does not change in a chemical reaction.

Tags

NGSS.MS-PS1-5

In the equation

magnesium + oxygen 🡪 magnesium oxide, Magnesium + oxygen is the reactant?

• true

• false

Tags

NGSS.MS-PS1-2