S 1.3

Question 1

What happens when a substance is heated?

Answer 1

-As a substance is heated the vibrational energy of its particles increases = temperature increases.
-Vibrations are sufficiently energetic for the particles to move away from their fixed positions.
-Energy added during this stage is used to break the inter-particle forces, not to raise the kinetic energy.
-Temp. remains constant

Question 2

Relation between celsius and kelvin

Answer 2

273 K = 0ºC
1ºC=1K

Question 3

How can matter be divided?

Answer 3

All matter
-Pure substance: compound, element
-Mixture: Homogeneous, Heterogeneous

Question 4

Define empirical formula

Answer 4

Simplest whole number ratio of atoms

Question 5

Method to calculate the empirical formula

Answer 5

1) Convert into moles
-By dividing by the Mr
2) Divide by the smallest number
3) Approximate to the nearest whole number

Question 6

How do you calculate the empirical formula when there are percentages

Answer 6

Mr of 1 specific element x mol / Total Mr of substance x 100

Question 7

Define molecular formula

Answer 7

The actual number of atoms in a molecule

Question 8

How can the molecular deduced from the empirical formula?

Answer 8

-Using the molar mass

(mass of empirical formula)x ) M where x is an integer

Question 9

Triangle for concentration

Answer 9

mass / conc x vol
always in dm^3

Question 10

What happens when a solution is diluted

Answer 10

The moles remain the same but because the volume increases the concentration decreases.

Question 11

Give an equation relating initial and final concentration

Answer 11

C1V1=C2V2
-1= initial
-2= final

Question 12

Define titration

Answer 12

Technique used to determine the concetration of a solution when reacting with a solution of known concetration.

Question 13

What is gas volume determined by?

Answer 13

Gas volume is determined by the number of particles and by the temperature and pressure

Question 14

What is avogadro’s law?

Answer 14

Equal volumes of all gases when measured at the same temperatures and pressure.
-v is directly proportional to n

Question 15

What is the ideal gas model?

Answer 15

1) Particles in a gas have negligible volume compare with the volume the gas occupies.
2) No intermolecular forces between particles except when the molecules collide
3) Particles have a range of speeds and move randomly
-Average kinetic energy is proportional to the temperature
4) Collisions of particles with the walls of the container and with eachother are elastic

Question 16

What is pressure?

Answer 16

Gast particles colliding with the walls of the container.

Question 17

What happens to the pressure when the temperature increases?

Answer 17

Collisions with walls are more energetic and more frequent

Question 18

What is the ideal gas equation

Answer 18

PV = nRT
-Real gases deviate from the ideal gas model
-R = Ideal gas constant
-n= amount of substance

Question 19

What is the combined gas equation

Answer 19

P1V1/T1 = P2V2/T2

Question 20

What happens to a Vol/temp graph if extended backwards?

Answer 20

-It could reach -273ºC
-Absolute 0

Question 21

What is charles’ law?

Answer 21

V is directly proportional to T (k)

Question 22

When calculating with gases which unit must we always use?

Answer 22

Kelvin!

Question 23

What is the molar volume?

Answer 23

WHen a volume occupied by 1 mol of a gas is the same for all gases when measured under the same conditions.
-0ºC
-100 kPa
-2.27 x 10^-2 m^3 mol^-1
-22.7 dm^3 mol ^-1

Question 24

Mole of gas formula with molar volume

Answer 24

mole of gas= volume / molar volume