Chemistry Ch. 11 and 12 Test:

What is one way you can tell if a chemical reaction has occured?

If a new substance (gas) has been produced.

What is the general procedure for solving a stoichiometric problem?

In a typical stoichiometric problem: • The given quantity is first converted to moles. • Then, the mole ratio from the balanced equation is used to calculate the number of moles of the wanted substance. • Finally, the moles are converted to any other unit of measurement related to the unit mole, as the problem requires.

How are mole ratios used in chemical calculations?

In chemical calculations, mole ratios are used to convert between a given number of moles of a reactant or product to moles of a different reactant or product.

How do you solve a mole to mole ratio?

In the mole ratio below, W is the unknown, wanted quantity and G is the given quantity. The values of a and b are the coefficients from the balanced equation x mol G = b mol W ______________ = Mol W a mol G

How would you balance this equation? Pb(s) + Ag+(aq) → Ag(s) + Pb2+

Placing the coefficient 2 in front of Ag+(aq) balances the charge.

What types of the five reactions mentioned in this chapter can be written as net ionic equation?

Single and Double replacement reactions.

Coefficients:

Small whole numbers that are placed in front of the formulas in an equation in order to balance it.

Stoichiometry:

The calculations of quantities in chemical reactions.

Calculate the number of grams of NH3 produced by the reaction of 5.40 g of hydrogen with an excess of nitrogen. The balanced equation is: N2(g) + 3H2(g) = 2NH3(g)

The coefficients of the balanced equation show that 3 mol H2 reacts with 1 mol N2 to produce 2 mol NH3. 5.40 g H2* 1 mol H2 2 mol NH3 ______________ * _________________ 2.0 g H2 3 mol H2

What are the five general types of reactions?

The five general types of reactions include combination, decomposition, single-replacement, double-replacement, and combustion.

How do you describe what happens in a chemical reaction?

The reactants are written on the left , and the products on the right with an arrow between them.

Interpret this equation in terms of a. numbers of representative particles and moles. b. masses of reactants and products. 2H2S(g) + 3O2(g) 2SO2(g) + 2H2O(g)

To calculate in number of representative particles and moles: Take the coefficent in front of each number and add moles/molecules after it. To calculate in masses of reactants and products: Use the periodic table, find the atomic weight of each element, and multiple it by the coefficent.

How do you write a skeleton equation?

To write a skeleton equation, write the chemical formulas for the reactants to the left of the yields sign (arrow) and the formulas for the products to the right.

Combination Reaction:

Two or more reactants combine to form a new single substance. Example: 2Mg(s) + O2 → 2 MgO(s)

Balanced Reaction:

Which each side of the equation has the same number of atoms of each element and mass is conserved.

Balance the follow reaction: H2O(l) = H2(g) + O2(g)

2H2(g) + O2(g)

Net ionic equation:

An equation for a reaction in solution that shows only those particles that are directly involved in the chemical change.

Complete ionic equation

An equation that shows dissolved ionic compounds as dissociated free ions. Example: Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) → AgCl(s) + Na+(aq) + NO3-(aq)

Spectator ion:

An ion that appears on both sides of an equation and is not directly involved in the reaction

Solve the following problem: How many moles of NH3 are produced when 0.60 mol of nitrogen reacts with hydrogen?

.60 mol N2 * 2 mol NH3 _________________ = 1.2 mol NH3 1 mol N2

What are the steps for solving a mass-mass problem?

1. Change the mass of G to moles of G 2. Change the moles of G to moles of W by using the mole ratio from the balanced equation. 3. . Change the moles of W to grams of W ) by using the molar mass of W.

In terms of what quantities can you interpret a balanced chemical equation?

A balanced chemical equation can be interpreted in terms of different quantities, including numbers of atoms, molecules, or moles; mass; and volume.

Decomposition reaction:

A chemical change in which a single compound breaks down into two or more simpler products. Example: 2NaN3(s) → 2Na(s) + 3N2(g)

Combustion reaction

A chemical change in which an element or a compound reacts with oxygen, often producing energy in the form of heat and light. A combustion reaction always involves oxygen as a reactant.

Single-replacement reaction:

A chemical change in which one element replaces a second element in a compound. You can identify a single-replacement reaction by noting that both the reactants and the products consist of an element and a compound. The elements on the outside end combine, and the elements on the inside end combine.

Double-replacement reaction:

A chemical change involving an exchange of positive ions between two compounds.They generally take place in aqueous solution and often produce a precipitate, a gas, or a molecular compound such as water.

Skeleton equation:

A chemical equation that does not indicate the relative amounts of the reactants and products.

Mole ratio:

A conversion factor derived from the coefficients of a balanced chemical equation interpreted in terms of moles.

Chemical Equation:

A representation of a chemical reaction; the formulas of the reactants (on the left) are connected by an arrow with the formulas of the products (on the right).

Catalyst:

A substance that speeds up the reaction but is not used up in the reaction.

If there is an odd number of atoms on the product side, how can you fix it?

By multiplying the product by the number of however many of that same atom are on the reactant side.

How can net ionic equations be simplified?

By removing the elements that remain unchanged on both sides of the equation.

How can you predict the formation of a precipitate in a double-replacement reaction?

By using the general rules for solubility of ionic compounds, you can predict the formation of a precipitate.

Balance the following equation: C2H6O(l) + O2(g) → CO2(g) + H2O(g)

C2H6O(l) + 3O2(g) → 2CO2(g) + 3H2O(g)

Balance the following equation. C3H8(g) + O2(g) → CO2(g) + H2O(l)

C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)

What is the difference between complete ionic equations and net ionic equations?

Complete ionic equations show all ions present in solution during a reaction. Net ionic equations show only those ions that are directly involved in the reaction. Ions that do not participate, known as spectator ions, are not shown in a net ionic equation.