Chemistry 2.13-.18

Which statement(s) is/are TRUE for all chemical reactions?

1. Energy is absorbed when bonds are broken. 2. Energy is released when bonds are formed. 3. Reactant elements and/or compounds rearrange to form chemically new products.

Which statement(s) is/are TRUE about reactants in chemical reactions?

1. Reactants are always written on the left side of the arrow in a chemical equation. 2. Reactions can sometimes go in both directions, reversing between reactants and products. 3. Reactants are present at the beginning of a reaction and rearrange to form new products.

A solid and a liquid are mixed in a test tube. Which of the following observations would indicate that a chemical reaction occurred between them?

1. The mixture starts to fizz as a gas is released. 2. The test tube becomes colder as the substances are mixed. 3. The mixture changes color to a deep blue.

Which of the following are types of chemical change?

1. Two elements form a compound. 2. A compound is broken down into its elements. 3. One compound is transformed into another compound.

Which of the following statements about REACTANTS are TRUE?

1. they are always written on the left side of the arrow in a chemical equation 2. they are the substance(s) required for a reaction to occur 3. they combine, break apart, or rearrange in order to make products in a reaction

How many hydrogen atoms are in one molecule of the compound C12H22O11?

22

Which of the following represents a synthesis reaction?

2H2+O2→2H2O

If you mix two clear, colorless liquids together, which of the following observations would indicate a chemical reaction has occurred?

A solid appears in the tube and settles to the bottom.

Which chemical equation represents a double replacement reaction?

AgNO3 + NaCl → AgCl + NaNO3

Which of the following may indicate a change in the chemical properties of matter?

Both A and B a. Precipitate formation b. change in heat energy

Which of the following statements best describes why burning a match would be considered a chemical reaction?

Burning a match forms new substances.

The numbers written after each chemical symbol in a formula are called subscripts. The subscript of hydrogen in H3PO4 is 3. The subscript for phosphorus is assumed to be 1 because no subscript is shown. Ethanol is a compound that consists of carbon, hydrogen, and oxygen in a 2:6:1 ratio. What is the correct chemical formula (with subscripts) for ethanol?

C2H6O

Which statement about the following reaction is TRUE? CH4 + 2O2 → 2H2O + CO2

CH4 and O2 are the reactants because they are found on the left side of the arrow.

Which of the following correctly describes changes in energy during a chemical reaction?

Energy may be either absorbed or released during a reaction.

T or F A liquid in a container is heated until it turns to a gas. This is enough evidence to determine that a chemical reaction occurred.

False

T or F A sample of metal is heated until it melts and begins to glow red. When it cools it appears the same as it did before it was heated. This is strong evidence that a chemical reaction has occurred.

False

T or F If a chemical is used in a chemical reaction as a reactant but no products are formed and nothing changes about the chemical, it is safe to assume it has no chemical properties.

False

T or F In the periodic table, the symbol 'S' is used for silicon and the symbol 'Si' is used for silver.

False

T or F Someone is working in their garden, giving some plants a liquid fertilizer to help them grow. They accidentally spill some of the fertilizer on a rock in their garden and notice the rock appears shiny and a little darker than it did when it was dry. After a while the rock dries and looks the same as it did before being covered in fertilizer. This likely means a chemical reaction has occurred between the rock and the fertilizer.

False

T or F The freezing of water is a chemical property because the structure of the water molecule is changed.

False

Which of the following is/are false?

Mixing of lemonade powder with water is a chemical change

The chemical symbols for radon, copper, and iron are _____, _____, and _____ respectively.

Rn, Cu, Fe

Which statement best describes what occurs during a chemical reaction?

The bonds in reactants break so that elements can rearrange and form new products.

If a powdered solid were mixed with a liquid which of the following observations would most clearly indicate a chemical reaction was occurring?

The mixture starts fizzing and releasing gas.

T or F A small piece of silvery metal is added to a large beaker of water and immediately erupts into flame. This is evidence that a chemical reaction is occurring.

True

T or F Aerobic respiration is an example of a chemical change.

True

T or F Battery charge and discharge is an example of a chemical change.

True

T or F Butter turning rancid is an example of a chemical change.

True

T or F Measurement of a physical property does not change the identity of the substance; however, measurement of a chemical property occurs as the identity of the substance changes.

True

T or F Poaching an egg for breakfast is an example of a chemical change.

True

T or F Tarnishing of jewelry is a chemical change.

True

T or F We can observe a chemical property during a chemical reaction.

True

Chemical changes include _____.

all of the above

Which of the following NEVER occurs during a chemical reaction?

atoms are destroyed

Which of these is a chemical change?

baking a cake

What are the products in the process described below? During cellular respiration, organisms use glucose and oxygen to generate carbon dioxide, water, and energy.

carbon dioxide, water, and energy

A ______ reaction is a process in which some substances change to other substances as chemical bonds break and reform.

chemical

Formation of a precipitate in a chemical reaction is considered a:

chemical change

A ______ ______ describes the ability of a substance to undergo a specific chemical change.

chemical property

A _______ ______ is a process that occurs when one or more substances are changed into one or more new substances. For example, when zinc and sulfur are mixed together with the addition of energy in the form of heat, zinc sulfide (ZnS) is produced.

chemical reaction

The process of burning a fossil fuel to release energy is called _____.

combustion

Which type of reaction is represented by the following chemical equation?CH4+2O2→CO2+2H2O

combustion reaction

Which of the following is an example of a chemical property?

corrosion

Besides matter, all chemical reactions require _____ in order for the reaction to occur.

energy

Two reactants are mixed in a test tube, and the test tube becomes very warm. This is a sign of a transfer of _____ taking place as a result of a chemical change.

energy

T or F A physical change occurs when food spoils.

false it is chemical

A chemical _____ is a set of chemical symbols that indicate the elements in a compound and the relative proportions of those elements.

formula

In the reaction, sodium+water→sodium hydroxide The products are ______ and sodium ______

hydrogen and hydroxide

When zinc metal is mixed with hydrochloric acid, vigorous production of what substance is an indication that a chemical reaction is occurring?

hydrogen gas

A handful of elements have been known since ancient times. Their symbols are based on what language?

latin

What are the reactants in the process described below? During photosynthesis, plants use light energy, carbon dioxide, and water to make glucose and oxygen.

light energy, carbon dioxide, and water

When two colorless _______ are mixed together, the formation of a solid precipitate is a strong indication that a chemical _____ has occurred.

liquids, gases, solutions and reaction

Which verb describes a process that is NOT indicative of a chemical change?

melt

Name the elements in the chemical formula. PF5

phosphorus and fluorine

Name the elements in the chemical formula KCN

potassium, carbon, and nitrogen

A solid that forms and settles out when two or more solutions are mixed is called a _____.

precipitate

The substances produced in a chemical reaction are called _____.

products

A(n) _____ is a substance that is present at the start of a chemical reaction that is converted into product(s).

reactant

The substances that start a chemical reaction are called _____.

reactants

_____ are the starting materials and are written on the left-hand side of the equation.

reactants

Which of the following is a chemical change?

rotting

Chemical symbol 'Ag' is used for which of the following elements?

silver

A one- or two-letter designation of an element is named as a chemical _____

symbol

A chemical equation describes a chemical reaction.

yes