Chemical Reactions and Compounds Test- Mrs. Cyr

Write a balanced chemical equation that shows the reaction between hydrogen (H2) and oxygen (O2) to form water. Identify the parts of the chemical equation.

2H2 + O2 ----> 2H2O

How many atoms of each element are in the following formulas: 3Fe2(CO3)3 - 2NaHCO3 -

3Fe2(CO3)3 - Fe=6 C=9 O=27 2NaHCO3 - Na=2 H=2 C=2 O=6

How is a chemical change different than a physical change?

A chemical change is different than a physical change because in a chemical change a new substance is formed and in a physical change no new substance is formed.

How does a precipitate form?

A precipitate forms when two liquids react and a solid is formed.

Why must chemical equations/reactions be balanced?

Balancing a chemical equation so that the same number of atoms of each element is found in both the reactants and the products is an example of the law of conservation of mass.

What causes chemical bonds in molecules to break?

Chemical bonds break because molecules bump into each other with enough energy to break them.

What is used to balance a chemical equation?

Coefficients are used to balance an equation.

What is the compound name? Fe(OH)2 - SCl4 - P4S5 - K2SO4 -

Fe(OH)2 - iron (II) hydroxide SCl4 - sulfur tetrachloride P4S5 - tetraphosphorus pentasulfide K2SO4 - potassium sulfate

What must be done for a chemical equation to be balanced?

For a chemical equation to be balanced, all atoms must be counted.

Which form of energy is released or absorbed in most chemical reactions?

Heat is the form of energy released or absorbed in most chemical reactions.

When there is no subscript in a chemical formula, what does that mean? What causes chemical bonds in molecules to break? Chemical bonds break because molecules bump into each other with enough energy to break them.

If a chemical symbol in a chemical formula has no subscript, it means only one atom of the element is in the molecule.

How can a solution be neutralized?

If a solution is acidic, adding a base can neutralize it. If a solution is basic, adding an acid can neutralize it.

What happens if we increase the amount of reactants? Why?

If more reactants are used in a chemical reaction, more products will be produced because more reactants have more atoms to react to form more products.

What happens in an endothermic reaction?

If two substances react and the temperature of the mixture decreases, the reaction is endothermic. If a reaction is endothermic it takes more energy to break the bonds of the reactants than is released when the bonds in the products are formed.

What happens in an exothermic reaction?

If two substances react and the temperature of the mixtures increases, the reaction is exothermic. In an exothermic reaction more energy is released when the bonds in the products are formed than is used to break the bonds in the reactants.

What happpens during a chemical reaction?

In a chemical reaction the atoms of the reactants unbond, rearrange, and then rebond to form the products.

How does heating the reactants change a chemical reaction?

In a chemical reaction, if the reactants are heated, the reaction usually happens faster.

What ions form in water molecules?

In any sample of water, there are always some water molecules, which have become ions. These ions are H3O+ and OH-

In any sample of water, how do water molecules become ions?

In any sample of water, there are always some water molecules, which have become ions. Transferring a proton from one water molecule to another produces these ions.

What is the charge of an ionic compound?

The charge of an ionic compound is zero (0).

What does the law of conservation of energy say?

The law of conservation of energy says that energy cannot be created or destroyed but can be change from one form to another.

What does the prefix in a chemical formula show?

The prefix in a chemical formula represents the number of atoms of each element.

What are the signs of a chemical reaction?

The signs of a chemical reaction are gas formation, solid formation (precipitate), color change and energy change.

What does it mean to say that mass is conserved?

To say that mass is conserved in a chemical reaction means that the type and number of atoms in the reactants equals the type and number of atoms in the products.

What happens when CO2 gas reacts with water?

When carbon dioxide (CO2) gas reacts with water, an acid is produced.

What happens to concentration of ions when a solution becomes more acidic?

When the pH of a solution becomes more acidic, the concentration of H3O+ ions increases.

What happens to pH when a solution becomes more acidic?

When the pH of a solution becomes more acidic, the number on the pH scale decreases.

What happens to the concentration of ions when a solution becomes more basic?

When the pH of a solution becomes more basic, the concentration of H3O+ ions decreases.

What happens to pH when a solution becomes more basic?

When the pH of a solution becomes more basic, the number on the pH scale increases.

What is the concentration of ions when the pH of water is neutral?

When the pH of water is neutral, there is an equal concentration of OH- and H3O+

Write the formula for each compound shown iodine pentafluoride - aluminum carbonate - iron (III) bromide - phosphorus pentabromide -

iodine pentafluoride - IF5 aluminum carbonate - Al2(CO3)3 iron (III) bromide - FeBr3 phosphorus pentabromide - PBr5