Chem- Ch.6

All of the statements regarding redox reactions are true

Alkali metals often behave as reducing agents because they readily lose electrons a reducing agent causes another substance to be reduced halogens usually behave as oxidizing agents because they readily gain electrons metal ions are produced when pure metals are oxidized

Combustion

An exothermic reaction between fuel and an oxidant that produces oxidized products

Precipitation reactions

An insoluble solid precipitate drops out of the solution and separates from the solution. This occurs when anions and cations of two ionic compounds change partners

What occurs in a chemical reaction?

Atoms in reactants are rearranged to form new bonds

Examples of chemical change include:

Bleaching, burning, rusting, fermenting

When the reaction shown is correctly balanced, the coefficients are Li + Br2 → LiBr

2, 1, 2

Which sample contains the largest number of atoms?

2.0 mol CH4

In the reaction shown, how many moles of HCl are needed to react with 2.4 moles of Al? 2 Al + 6 HCl → 2 AlCl3 + 3 H2

2.4 x 6/2 =7.2

How many molecules are present in 3.25 mol of C2H6O?

3.25 x 6.002x10^23 = 1.96x10^24

What is Avogadro's number?

6.022x10^23

What is a physical change?

A change in the state of a substance but does not involve a change in the identity or composition of the substance

What is a chemical change?

A change of one substance into a new substance that has different properties

Which statement concerning the mole is not correct?

A mole of any compound contains one mole of each kind of atom found in that compound

In a double replacement, positive ions in reacting compounds switch places

AB + CD --> AD+ CB

Acid base neutralization

Acid reacts with base to yield water and an ionic compound called a salt

How many moles are present in 100.0 g of Al?

Converting grams to moles

Example: What is the mass of 3.987 mol of Al?

Converting moles to grams

In the reaction shown, ________ is the oxidizing agent because it ________

CuCl2; gets reduced

Which combination of ions most likely to produce a precipitate?

FE3+ OH-

True/ false: One mole of methane, CH4, contains the same number of atoms as one mole of carbon dioxide, CO2.

False

True/ false: when a substance is oxidized its charge (or oxidation number) decreases

False

Which reaction is an example of both a precipitation and a neutralization?

H2SO4 (aq) + Ba(OH)2 (aq) → BaSO4 (s) + 2 H2O (l)

What is Oxidation?

Loss of electrons, but if electrons are added to right side of equation, it is also oxidation. Oxidation will always occur on the right side of equation.

Which combination of ions are least likely to produce a precipitate?

MG2+ C2H3O2-

How do you find average mass?

Add all masses of each substance together. Ex: CHCl3 1 C = 12.01 1 H = 1.008 3 Cl = 3 x 35.45 = 106.35 12.01 + 1.008 + 106.35 = 119.37 The average mass of CHCl3 is 119.37

The number of grams in 7.00 moles of N2

N=14 14x2=28 28x7=196

Can subscripts be changed when balancing a chemical equation

NO

Which of the following is always a spectator ion in a chemical reaction?

Na+

The number of grams in 0.350 mol of Na is

Na= 23 (round up) 0.350x23=8.05

Which statement concerning the mole concept is not true?

One mole of any compound contains one mole of atoms

Is loss of hydrogen oxidation or reduction?

Oxidation

What is Reduction?

Reduced charge. Addition of electrons on left of equation is also reduction. Reduction will always occur on the left of equation

Is a gain of hydrogen oxidation or reduction?

Reduction

The Law of Conservation of Mass is

The scientific principle which is the basis for balancing chemical equations

Which combinations are least likely to produce a precipitate?

Those that are both soluble

Which combinations are most likely to produce a precipitate?

Those that are insoluble and soluble in water

True/ False: For every mole of a substance, you have 6.022x10^23 number of atoms

True

How many moles of oxygen react with hydrogen to produce 27.6 mol of H2O? 2H2+O2⟶2H2O

Use the stoichiometric ratio: 1mol O2/ 2mol H2O

Consider the reaction shown and identify the statement that is not true CaCO3 (s) 825C--> CaO (s) + CO2 (g)

Water must be present for this reaction to occur

For an equation needing to know the amount of grams, the conversion order should be

grams --> moles --> moles --> grams

When a solution of iron(III) nitrate is mixed with a solution of sodium hydroxide, a rust colored precipitate forms. This precipitate is probably

iron(III) hydroxide

When a substance loses electrons it is ________; the substance itself is acting as a(an) ________ agent

oxidized, reducing

The element chlorine is very reactive as a(an) ________ agent because it readily ________ electrons to form the chloride ion

oxidizing, gains

The oxidation number of iron in the compound FeBr3 is?

+3

The oxidation number of chlorine in the compound FeCl3 is

-1

In the balanced reaction shown, the mole ratio of Fe2S3 to O2 is Fe2S3 + 4 O2 → 2 FeO + 3 SO2

1 to 4

How many grams are there in 1.50 × 1025 atoms of carbon?

We know that one mole of carbon, has a mass of 12 grams (look on the periodic table) We also know that for every mole we have 6.022x10^23 atoms Therefore to find atoms we would set up an equation like this:

Do ionic equations break down to net ionic equations?

Yes

What is a spectator ion?

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

Example:

calculating kilograms of glucose to moles