Chemical Reaction Changes Quizs

What happens to the total mass of the atoms involved in a chemical reaction?

• It will decrease if two molecules combine to form a single compound.

• It will stay the same no matter how the atoms are rearranged.

• It always changes as the atoms are rearranged into new molecules.

• It will increase if a new compound is formed during the reaction.

Jayne's science teacher mixed a clear liquid with a blue liquid in a beaker. After a few minutes there was a white solid at the bottom of the beaker. What is most likely true about the white solid?

• It was secretly added to the beaker by the teacher.

• It will dissolve in the solution when stirred.

• It is a new substance with different properties.

• It will dissolve in water to form a blue solution.

Which is the correct conclusion based on the data?

• A. A chemical reaction did not occur because physical properties, such as boiling point, do not change.

• B. A chemical reaction took place because the same elements were present before and after the change occurred.

• C. A chemical reaction occurred because the chemicals that were combined have different boiling points than the chemicals produced.

• D. A chemical reaction did not occur because both zinc and zinc chloride are known to be solids at room temperature.

Calcium carbonate (CaCO3) is heated and decomposes to form calcium oxide (CaO) and carbon dioxide (CO2). Which statement is true about the difference between calcium carbonate and calcium oxide?

• Calcium oxide has the same physical properties and the same chemical properties.

• Calcium oxide has different physical properties and different chemical properties.

• Calcium oxide has the same physical properties and different chemical properties.

• Calcium oxide has different physical properties and the same chemical properties.

A teacher is demonstrating physical and chemical changes to her class. Which action should she use to demonstrate a chemical change?

• cutting a piece of paper
• folding a piece of paper
• tearing a piece of paper
• burning a piece of paper

Which statement describes a change that occurs during a chemical reaction?

• Atoms in the original substances are changed into different atoms to make new substances.

• The atoms in a substance start to move faster until they are no longer touching each other.

• The atoms in a substance change their properties so they can become a new substance.

• Atoms in the original substances are arranged in a different way to make new substances.

Which is NOT an indicator of a chemical change?

• temperature change
• formation of a precipitate
• shape change
• production of light

Twenty-four grams of magnesium metal reacts with sixteen grams of oxygen gas to form magnesium oxide. According to the law of conservation of mass, how much magnesium oxide will there be after the chemical change is complete?

• 16 g

• 30 g

• 40 g

• 24 g

When substances with different chemical properties are formed, you have seen a -

• physical change
• chemical change

Iron reacts with sulfur to form iron sulfide. If 60 grams of iron reacts with sulfur to produce 90 grams of iron sulfide, how much sulfur has been used in the chemical reaction?

• 60 grams

• 30 grams

• 150 grams

• 120 grams