Moles 3 - solutions and gases

Question 1

How do you convert cm3 into dm3?

Answer 1

divide by 1000

Question 2

What is the concentration?

Answer 2

how much solute is present in a given volume of solution

Question 3

What is the concentration equation?

Answer 3

moles / volume

Question 4

How do you change moldm3 into gdm3?

Answer 4

xMr

Question 5

how do you work out the dilution scale factor?

Answer 5

old vol/ new vol

Question 6

What is the standard solution in titrations?

Answer 6

the solution with the known concentration

Question 7

What is the titration method?

Answer 7

1. do a rough titration first to get an approxiate idea of the volume of the solution in the biurette needed for the reaction
2. measure out an exact volume of the standard solution using a pipette and place it in the conical flask
3. add the second solution from a burette, swirling constantly, until just enough has been added to cause a reaction. this is usually indicated by a colour change by an indicator - repeat
4. find the mean of the concordant results and leave any outliers

Question 8

What is the titre?

Answer 8

the volume of solution in the biurette needed for the neutralisation reaction

Question 9

How do you make a standard solution?

Answer 9

1. weigh the salt on a balance in a weighing boat
2. add water to a beaker to dissolve the salt and use a rod to stir to ensure it has all dissolved
3. transfer the solution in the beaker into a volumetric flask by using distilled water to wash out the beaker and rod to ensure all the solution is in the volumetric flask
4. top up the volumetric flask with water using a pipette to the volume that you need
5. invert several times to ensure the solution is all mixed

Question 10

What is the molar gas volume?

Answer 10

the volume per 1 mole of gas molecules at a stated temperature and pressure
at room temp and pressure the molar gas vol is 24.0 dm3mol-1

Question 11

What is the equation for the moles of gas in room temp and pressure?

Answer 11

moles of gas = vol / 24.0

Question 12

What is the ideal gas equation?

Answer 12

PV = nPRT
p = pressure in Pa (KPA x 1000)
V = volume in m3
n = moles
R = gas constant - 8.314Jmol1K-1
T = temp in K (C’ + 273)

Question 13

What is the density equation?

Answer 13

density = mass/ vol

Question 14

What are the assumptions of the ideal gas equation?

Answer 14

there is a random movement of molecules
elastic collisions
negligible size
no intermolecular forces