conc + vol

Question 1

What is concentration?

Answer 1

Is a measure of How much solute is dissolved in a given solvent

Question 2

What is the formula linking volume and concentration?

Answer 2

Number of moles = concentration (mol/dm^3) x volume (dm^3)

Question 3

Calculate the number of moles dissolved in 10 dm^3 of a 2 mol/dm^3 solution.

Answer 3

N=cxv
2x10
20 moles

Question 4

What is the difference between concentrated and dilute solutions?

Answer 4

Concentrated: large amount of solute per dm^3 of solvent
Dilute: small amount of solute per dm^3 of solvent

Question 5

In a mixture of 100 cm^3 of 0.1 mol dm^3 KCl(aq) and 100 cm^3 of 0.1 mol/dm^3 of K2CO3 (aq) ,
What is the total concentration of k^+ ions in the mixture formed?

Answer 5

KCl,
V= 0.1dm^3
C= 0.1 mol/dm^3 
Moles = 0.1x0.1
= 0.01
K2co3 
Moles = 0.1x0.1
=0.01 moles
0.01x2
=0.02

0.02+0.01
=0.03 moles of potassium ions produced

0.03 =c x 0.2
C=0.15 mol/dm^3

Question 6

Citric acid is an acid used to add a sour taste to drinks and sweets. Calculate the amount in mol of citric acid in 25.00 cm^3 of 0.01 mol/dm^3

Answer 6

0.025x0.01

=0.00025 mols

Question 7

Phosphoric acid,H3PO4 can take part in the reaction shown in the equation: 3NaOH(aq) +H3PO4 (aq) -> Na3PO4(aq) + 3H2O(l)
Calculate the volume of 0.1 mol/dm^3 of NaOH that reacts exactly with 30 cm^3 of 0.1 mol/dm^3 of H3PO4.

Answer 7

C=0.1 MOL/DM
V= 0.03 dm3
N=0.003mol
1mol hp :3 naoh’->0.009 mol naoh 
C=0.1mol/dm3

V-> 0.009/0.1
=0.09dm3
= 90 cm^3

Question 8

A student dissolves 6 g of MgCl2 in 100cm3 of water. What is the concentration of chloride ions in the resulting solution?

Answer 8

Mass/mr
= 6/243+71
- 0.0630 mol
Mol of cl- 
= 0.0630 x 2
=0.126 moles of chloride ions
C = 0.126/0.1
1.26 mol/dm3