2/28 Evidence of Chemical Reactions & Counting Atoms

A chemical equation for the reaction between calcium hydroxide, Ca(OH)₂, and sulfuric acid, H₂SO₄, is shown. The masses of some of the reactants and products are given in grams. How many grams of sulfuric acid were used in the reaction?

• 62 g

• 98 g

• 36 g

• 100 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which statement describes an action that most likely resulted in a chemical reaction?

• A pan of water was heated on a stove, and steam formed.

• A liquid was mixed with another liquid, and a precipitate formed.

• A liquid was sprayed into the air, and a sweet odor was smelled.

• A child blew through a wand filled with soap, and bubbles were produced.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of these observations is an indication that a chemical reaction has occurred?

• Steam forms above boiling water.

• A solid forms when a clear solution is frozen.

• A solid forms when two clear solutions are mixed.

• Sugar crystals form on the sides of a boiling pot of sugar water.

Tags

NGSS.MS-PS1-2

Students mixed two liquids in a beaker and listed their observations. Based on these observations, which statement contains the best evidence that a chemical reaction occurred?

• There is a change in shape.

• There is a change in volume.

• The two liquids mix into a solution.

• The two liquids form a new substance.

Tags

NGSS.MS-PS1-2

Two solutions are mixed and react to produce the solid precipitate AgCl. The chemical reaction is shown by the balanced chemical equation. What happens to the total mass as the reaction takes place?

• The mass increases.

• The mass decreases.

• The mass remains constant.

• The mass first decreases and then increases.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Oxygen and oxygen-containing compounds are involved in many different reactions. Which balanced equation represents a reaction that involves 14 atoms of oxygen?

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• 
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Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

The names and chemical formulas of four substances are shown in the chart. Which substance listed in the chart is made up of the most atoms?

• Carbonic acid

• Nitric acid

• Phosphoric acid

• Sulfuric acid

Tags

NGSS.MS-PS1-1

A compound secreted by honeybees to paralyze intruders in their hives is known as 2-heptanone. The formula for this compound is shown. How many atoms of each element are in one molecule of 2-heptanone?

• 4 carbon atoms, 11 hydrogen atoms, and 1 oxygen atom

• 7 carbon atoms, 14 hydrogen atoms, and 1 oxygen atom

• 7 carbon atoms, 11 hydrogen atoms, and 8 oxygen atoms

• 6 carbon atoms, 14 hydrogen atoms, and 3 oxygen atoms

Tags

NGSS.MS-PS1-1

Which chemical reaction involves the fewest oxygen atoms?

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• 
• 

Tags

NGSS.MS-PS1-1

Strontium phosphate, Sr₃(PO₄)₂, is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula for Sr₃(PO₄)₂?

• 2

• 3

• 4

• 8

Tags

NGSS.MS-PS1-1