Chemistry Test Chp 10

What is a chemical reaction?

The process by which one or more substances are changed into one or more different substances

What is the Law of Conservation of Mass?

The total mass of the reactants must equal the total mass of products for any given chemical reaction

What does a chemical equation represent?

With symbols and formulas it represents the identities and relative amounts of the reactants and products in a chemical reaction

What are indications of a chemical reaction?

Heat and light emitted

Production of a gas

Formation of a precipitate

Color change

What are characteristics of chemical equations?

Equation must represent all known facts

Must contain the correct formulas for the reactants & products

The law of conservation of mass must be satisfied

What are diatomic molecules?

They do not exist as a single molecule

What are the diatomic moelcules?

H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂

What is a way to memorize the diatomic molecules?

HOFBrINCl

What are coefficients used for in a chemical equation?

To equalize the # of atoms, coefficients are added where necessary

Small whole # in front of a chemical formula.

If no coefficient, assume to be 1

What is a word equation?

A word equation is an equation where reactants and products are represented by words

Does not give amount of reactants/products

What is an example of a word equation?

Methane + oxygen → carbon dioxide + water

What does a formula equation represent?

A formula equation represents the reactants and products of a chemical equation by their symbols or formulas

What does a balanced formula equation provide?

Both qualitative and quantitative data

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

What are the states of reactants and products?

(s) - solid

(l) - liquid

(g) - gas

(aq) - aqueous: "Dissolved" in water

What do coefficients indicate?

Coefficients indicate relative amounts of reactants and products

What does a chemical reaction give?

The smallest whole number ratio

What can relative mass of products/reactants be determined from?

Reaction's coefficients

What does the reverse reaction have the same amount as?

The reverse reaction has the same relative amounts of substances as the forward reaction

What are the rules to balancing chemical equations?

List atoms on both sides of the reaction

Balance different atoms one at a time

1st balance elements that appear only once on each side of the equation

Balance polyatomic ions that appear on both sides of the equation

Balance H and O LAST

Count to make sure atoms of the same elements are equal

What is methane?

CH₄

What must you assume while balancing chemical equations?

Everything is unbalanced

What are the types of chemical reactions?

Synthesis, decomposition, single replacement, double displacement, and combustion

What is a synthesis reaction?

A synthesis/composition reaction is when two or more substances combine to form one new product

A + X -> AX

What are oxides?

Reactions of elements with oxygen produce an oxide of the element

Both metals and non-metals!

2Mg(s) + O₂(g) -> 2MgO(s)

S₈ (s) + 8O₂(g) ->

What do most metals react with?

Most metals react with group 17 elements (halogens) to form ionic compounds (halides)

Group one forms MX - NaCL -> 1:1 ratio

Group two forms MX₂ -MgF₂ -> 1:2 ratio

What element is particularly reactive with metals?

Fluorine

How is metal hydroxides formed?

Oxides of active metals (highly reactive metals) react with water to form metal hydroxides

CaO (s) + H₂O (l) -> Ca(OH)₂

How are oxyacids formed?

Many oxides of non-metals react with water to produce oxyacids

Acid rain = non metal oxide + H₂O

Nonmetal oxide = SO₂ or NO₂

What is a decomposition reaction?

A single compound undergoes a reaction that produces 2 or more simpler substances (opposite of a synthesis reaction)

AX -> A + X

When can a decomposition reaction take place?

A decomposition reaction can only take place when energy, in the form of electricity or heat, is added

What does decomposition of binary compounds turn into?

Decomposition of Binary compounds breaks compound into its elements

Do oxides of less active metals decompose?

Yes, oxides of less-active metals also decompose into their elements when heated

What do metal carbonates break down to produce?

Metal carbonates break down to produce a metal oxide and CO2 gas

CaCO₃, MgCO₃

What do metal hydroxides yield?

Metal hydroxides (except group 1) yield metal oxides and water

What do metal chlorates produce?

Metals chlorates produces a metal chloride and oxygen

Fe(ClO₃)₃ + CaClO₂

What is a single replacement reaction?

One element replaces a similar element in a compound

A + BX -> AX + B

Y + BX -> BY + X

Where do single replacement reactions usually occur?

In aqueous solutions

What does metal replace in single replacement reactions?

Metal replaces metal in a compound

What occurs during a replacement of hydrogen in water by a metal in a single replacement reaction?

Group 1 elements react vigorously with water to produce metal hydroxides and hydrogen gas

Less-active metals react to produce metal oxides and hydrogen gas

What occurs during the replacement of hydrogen in an acid by a

metal?

More active metals can replace the hydrogen in acids like, HCl, and H2SO4 to produce a metal compound (salt) and

hydrogen gas

What occurs during the replacement of halogens?

One halogen can replace another less-active halogen

Each halogen is less active than the one above it

What are double replacement actions?

The ions of two compounds exchange places in an aqueous solution to form two new compounds

AB + CD → AD + CB

What are double replacement reactions like?

One compound is usually a precipitate, an insoluble gas, or a molecular compound like water

The other compound formed is soluble and remains in solution

What is a precipitate?

A precipitate is an insoluble (or slightly soluble) compound

How does a precipitate form?

Precipitate forms because of the strong attractive forces between ions

How does a gas form?

Insoluble gas forms and bubbles out of the solution

How does water form?

Very stable molecular compound (water) forms

What are combustion reactions?

A substance combine with oxygen releasing a large amount of energy in the form of light and heat

What is an example of a combustion reaction?

The burning of natural gas, propane, gasoline, and wood are combustion reactions

What are the most reactive metals?

Potassium, Sodium, Calcium, Magnesium, Aluminum, Zinc, Iron, Tin and Lead are more reactive than hydrogen

What are the least reactive metals?

Copper, Mercury, Silver, and God are less reactive than hydrogen

What elements react with H+ (aq) and H₂O (l) to make H₂ (g)?

Lithium, Potassium, Barium, and Calcium

What elements react with H+ (aq) and H₂O (g) to make H₂ (g)?

Magnesium, Aluminum, Manganese, Zinc, Chromium, and Iron

What elements react with H+ (aq) to make H₂ (g)?

Cobalt, Nickel, and Tin

What elements do not react with H+ (aq)?

Copper, Silver, Mercury, Platinum, and Gold

Think jewelry

When using subscript with hydroxide what do you need to add?

Parentheses - (OH)₂

What are examples of synthesis reactions?

Elements + oxygen -> "oxide" compound (can be metal/nonmetal oxides)

Elements + elements -> compound

Compound + compound -> compound

Metal oxide H₂O -> metal hydroxide

What is the formula for single replacement reactions?

A + BX -> AX + B (cation swapped out for cation)

Y + BX -> BY + X (anion swapped out for anion)

Cation is written first (positive ion)

How can you tell from the periodic table which elements are most active when bonding with another element?

Diagonal trend - Li most active while Au/Pt least active

In single replacement reactions what does metal replace in water?

Metal replaces H in water