Chapter #5 - Chemical Calculations

Question 1

What is the defenition of relative mass?

Answer 1

Mass of a substance compared to carbon.

Question 2

What is the defenition of mole (amount)?

Answer 2

Mass of a substance required to have 6 x 10^23 atoms.

Question 3

What elements exist only as individual atoms?

Answer 3

Noble gases

Question 4

What is the table to find the empirical formulae of a substance?

Answer 4

Question 5

What is the defenition of empirical?

Answer 5

Derived from experiments.

Question 6

What is the defenition of empirical formula?

Answer 6

Chemical formula calculated from an experiment, expressed as the lowest ratio of elements.

Question 7

What is Ar?

With the “r” small at the bottom.

Answer 7

Relative atomic masss.

Question 8

What is 0.2/ 0.4/ 0.6

Answer 8

1/5

Question 9

What is 0.25/ 0.75?

Answer 9

1/4

Question 10

What is 0.33/ 0.67?

Answer 10

1/3

Question 11

What is 0.5?

Answer 11

1/2

Question 12

What does the molecular formula represent?

Answer 12

It tells you how much atoms there are in the molecule (represents how they are bonded).

Question 13

Ionic structuer=

Answer 13

Lattice of alternating cations and anions arranged ina pattern held together with electrostatic forces.

Question 14

What is in between particles?

Answer 14

There are spaces (nothing)

Question 15

How do you represent when something is not bonded but is in the spaces between that atoms in an equation?

Answer 15

.

Question 16

What is a hydrated compound?

Answer 16

A compund that has water in its spaces.

Question 17

What is it called when a compound has nothing in its spaces?

Answer 17

Anhydrous.

Question 18

What does the size of the spaces between the particles in a molecule depend on?

Answer 18

The ratio of ionic radii.

Question 19

What can fit in some of the spaces between atoms in a molecule?

Answer 19

SMALLER water molecules.

Question 20

What does the Mr mean?

Answer 20

The mass needed to have 6 x 10^23 molecules

Question 21

How do you calculate the molecular formula from the emperical formula table?

Answer 21

Multiply the Ar to the ratio in all the elements, than add all those products. Divide the Mr from the sum of what you just got. Multiply the new product you just got and multiply it to the molecule.

Question 22

What is the chemical test for water?

Answer 22

Anhydrous copper sulfate => white => blue

Question 23

What are the steps to find mass of a substance in a reaction?

Answer 23

1. Write a balanced symbol eqn.
2. Calculate the no. of mols of the chemical given.
3. Use the co-efficients from the eqn, to determine the n. of the 2nd substance (Chemical you have to chemical you want).
4. Convert the n. into mass/ volume/ concentration.

Question 24

What are the steps to find volume of a substance in a reaction?

Answer 24

1. Write a balanced symbol eqn.
2. Calculate the no. of mols of the chemical given.
3. Use the co-efficients from the eqn, to determine the n. of the 2nd substance (Chemical you have to chemical you want).
4. Convert the n. into mass/ volume/ concentration. (REMEMBER TO USE VOLUME AS INSTEAD OF MASS)

Question 25

What does the volume of a gas depend on?

Answer 25

1. The no. of moles 2. The temperature (directly proportional) 3. The preassure (inversley proportional)

Question 26

What is stp?

Answer 26

Standard temp. preassure = 0 celcius,101000, 1 atm

Question 27

What is rtp?

Answer 27

rtp (room temp.) = 20 celcius, 101000 Pa, 1 atmpstphere

Question 28

What is the rule for how much volume the same no. of gas particles occup

Answer 28

The same no. of particles of **any** gas always occupies the same volume of space.

Question 29

What is the stp.and rtp, of 1 mol of any gas?

Answer 29

stp. = 22400cm3 rtp. = 24000cm3

Question 30

What is the defenition of limiting reagent?

Answer 30

The reactent that is not in excess.

Question 31

What is mass concentration?

Answer 31

The measure of the concentration of a solution in terms of the mass of rge solute, in grams, dissolved per cubic decimeter of solution (g/dm^3)

Question 32

What is molar concentration?

Answer 32

The measure of the concentration of a solution in terms of the number of moles of the solute dissolved per cubic decimetre of solution (mol/dm^3)

Question 34

What do you use when calculating the product made? (limiting reagent or excess reagent)

Answer 34

The limiting reagent.