Review Chemical Reactions

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction

• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants

• Mass is created in a physical change

• Mass is never created or destroyed

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What will weigh more when a chemical change is complete? The reactants before the chemical reaction, or the product after the reaction is complete?

• They both will weigh the same

• The reactant will weigh more than the product

• The product always weighs more than the reactant

• They both will loose mass after the reaction

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student measures the mass of a beaker containing water to be 300 grams (g). She adds table salt to the beaker and stirs until all of the salt is dissolved and the solution is clear. How does the addition of salt affect the mass of the beaker and its contents?

• The mass of the beaker and its contents is still 300 g.

• The mass of the beaker and its contents is now less than 300 g.

• The mass of the beaker and its contents is now greater than 300 g.

• The mass of the beaker and its contents depends on whether new atoms are formed.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

After a piece of paper is burned, the ashes weigh less than the original paper.

Which statement best explains this difference in mass?

• The particles of the paper change state from solid to gas, so the ashes weigh less than the original paper.

• The particles of the paper were chemically changed resulting in new substances that include gases.

• Some of the particles of paper have been destroyed, so it weighs less.

• Some of the particles of the paper have been transformed into heat.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Matter can not be created nor destroyed: it can only be

• Destroyed a little bit

• Transformed, changed

• Invisible

• None of the above

Tags

NGSS.MS-PS1-5

A chemistry student conducted several different procedures. Which of the following procedures best demonstrates the law of conservation of mass?

• using filter paper to separate 2 grams of solid powder from 10 grams of water

• combining 3 grams of copper and 4 grams of sulfur to make 7 grams of copper sulfate

• after burning 2 kilograms of wood from a pine tree, 0.4 kilogram of ash and soot remain

• evaporating 5 grams sugar water leaves 5 grams of sugar and turns the water into water vapor

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

On a warm day, Bridget places an open bottle of water outside in a sunny area. Later, she notices that there is less water in the bottle than there was earlier. What most likely happened to the water that is no longer in the bottle?

• Energy from the Sun destroyed the water.

• Energy from the Sun compressed the volume of the water.

• Energy from the Sun changed liquid water into water vapor.

• Energy from the Sun transformed the water into another compound.

Tags

NGSS.MS-ESS2-4

NGSS.MS-PS1-4

Coffee is a solution made by placing coffee grounds into a paper filter and then pouring very hot water over the coffee grounds. Which statement below correctly identifies the solute and the solvent of this solution?

• The coffee grounds are the solvent and water is the solute

• The coffee grounds are the solvent and the paper filter is the solute

• The coffee grounds are the solute and the water is the solvent

• The coffee grounds are the solute and the paper filter is the solvent

Which is NOT a characteristic of mixtures?

• A mixture can consist of a single element.

• A mixture can be separated by physical means.

• A mixture can be a solution.

• A mixture can be homogeneous or heterogeneous

Which characteristic applies to all mixtures, including solutions?

• Mixtures must be composed of compounds.

• Mixtures are composed of a single element.

• Mixtures are composed of two or more substances.

• Mixtures have uniform structures throughout entire samples.