Chem 210: Chapter 5 Book

Front 1

What is a chemical reaction?

Back 1

They involve breaking bonds in the starting materials, called reactants, and forming new bonds in the products.

* Converts one substance to another.

Front 2

What is a chemical equation?

Back 2

It is an expression that uses chemical formulas and other symbols to illustrate what reactants constitute the starting materials in a reaction what products are formed.

Front 3

How do you write a chemical equation?

Back 3

The reactants are on the left and the products on the right separated by a horizontal arrow called the reaction arrow.

Front 4

What are coefficients?

Back 4

The numbers written in front of any formula/

*Show the number of molecules of a given element or compound that react or are formed.

Front 5

What is the law of conservation of matter?

Back 5

Atoms cannot be created or destroyed in a chemical reaction.

Front 6

How to balance a chemical equations?

Back 6

1. Write the equation with the correct formulas

2. Balance the equation with coefficients one element at a time.

3. Check to make sure that the smallest set of whole numbers is used.

Front 7

What is a mole?

Back 7

It is a quantity that contains 6.02 x 10^23 items - usually atoms, molecules, or ions.

Front 8

How do you multiply two numbers in scientific notation?

Back 8

Multiply the coefficients together and add the exponents in the powers of 10.

Front 9

How do you divide two numbers in scientific notation?

Back 9

Divide the coefficients and subtract the exponents in the powers of 10.

Front 10

What is the formula weight?

Back 10

It is the sum of the atomic weight of all the atoms in a compound, reported in atomic mass units (amu).

Front 11

What is molar mass?

Back 11

It is the mass of one mole of any substance, reported in grams per mole.

* The value of it of an element in the periodic table is the same as the value of its atomic weight (amu).

Front 12

How do you convert moles of reactant to grams of product?

Back 12

1. Convert the number of moles of reactant to the number of moles of product using a mole-mole conversion factor.

2. Convert the number of moles of product to the number of grams of product using the product's molar mass.

Front 13

How to convert grams of reactant to grams of product?

Back 13

1. Convert the number of grams of reactant to the number of moles of reactant using the reactant's molar mass.

2. Convert the number of moles of reactant to the number of moles of product using a mole-mole conversion factor.

3. Convert the number of moles of product to the number of grams of product using the product's molar mass.

Front 14

What is oxidation?

Back 14

The loss of electrons from an atom.

* Gain of oxygen atoms or the loss of hydrogen atoms.

Front 15

What is reduction?

Back 15

The gain of electrons by an atom.

* The loss of oxygen atoms or the gain of hydrogen atoms.

Front 16

What is a redox (oxidation-reduction) reaction?

Back 16

It involves the transfer of electrons from one element to another.

It always has two components - one that is oxidized and one that is reduced.

Front 17

What is an oxidizing agent?

Back 17

A compound that gains electrons (is reduced) while causing another compound to be oxidized.

Front 18

What is a reducing agent?

Back 18

A compound that loses electrons (is oxidized) while causing another compound to be reduced.

Front 19

How do we decide which element or ion gains or loses electrons?

Back 19

- When neutral atoms, metals lose electrons and nonmetals gain electrons

- When ions, cations tend to gain electrons and anions tend to lose electrons.

Front 20

Breaking a bond requires ____, while forming a bond ______ energy.

Back 20

Energy.

Releases.

Front 21

What is the heat of reaction or the enthalpy change? (delta H)

Back 21

The energy absorbed or released in any reaction.

Front 22

When energy is absorbed the reaction is _________ and delta H is _________.

Back 22

Endothermic.

Positive (+).

Front 23

When energy is released, the reaction is said to be _______ and delta H is ______.

Back 23

Exothermic.

Negative (-).

Front 24

When delta H is negative, more energy is ______ in forming bonds than is needed to break bonds. The products are _____ in energy than the reactants.

Back 24

Released.

Lower.

Front 25

When delta H is positive, more energy is need to ______ bonds than is released in forming bonds. The reactants are _____ in energy than products.

Back 25

Break.

Lower.

Front 26

What is the energy of activation?

Back 26

The difference in energy between the reactants and the transition state.

Front 27

What is the energy barrier?

Back 27

The energy activation is called this, and it must be crossed.

Front 28

When the energy of activation is high, few molecules have enough energy to cross the energy barrier and the reaction is ____.

Back 28

Slow.

Front 29

When the energy of activation is low, many molecules have enough energy to cross the energy barrier and the reaction is ____.

Back 29

Fast.

Front 30

Increasing the concentration of the reactants _____ the number of collisions, so the reaction rate _____.

Back 30

Increases.

Increases.

Front 31

Increasing the temperature _____ the reaction rate.

Back 31

Increases.

Front 32

What is a catalyst?

Back 32

It is a substance that speeds up the rate of a reaction. It is recovered unchanged in a reaction, and it does not appear in the product.

Front 33

What is a reversible reaction?

Back 33

It can occur in either direction, from reactants to products or from products to reactants.

Front 34

What is equilibrium?

Back 34

When the rate of the forward reaction equals the rate of the reverse reaction, the net concentrations of all species do not change and the system is at this.

Front 35

What is Le Chatelier's principle?

Back 35

If a chemical system at equilibrium is disturbed or stressed, the system will react in the direction that counteracts the disturbance or relieves the stress.