10 minutes maximum! Can you do it in 5?
1. Which of these is the correct formula for the number of moles in solution?
  • A.   number of moles = concentration x volume in cm3
  • B.   number of moles = concentration x volume in dm3
  • C.   number of moles = concentration ÷ volume in cm3
  • D.   number of moles = concentration ÷ volume in dm3
2. The amount, in moles, of KOH in 25.0cm3 of 0.150 mol/dm3 potassium hydroxide solution is:
  • A.   3.75 mol    
  • B.   0.00375 mol    
  • C.   6.00 mol       
  • D.   0.00600 mol 
3. The volume of 0.500 mol/dm3 sulfuric acid which contains 0.0450 moles of sulfuric acid is:
  • A.   0.0225 cm3       
  • B.   0.0900 cm3        
  • C.   22.5 cm3             
  • D.   90.0 cm3

Q4+5.

A student made a standard solution of sodium hydroxide by dissolving 10.0g of sodium hydroxide, NaOH, in distilled water to make 250cm3 of solution.

[Mr: NaOH = 40]

 

 volumetric flask
H Padleckas | CC BY-SA 2.5
4. Calculate the amount, in moles, of sodium hydroxide used.
  • A.   0.250         
  • B.   4.00        
  • C.   400          
  • D.   2.50
5. Calculate the concentration, in mol/dm3, of the sodium hydroxide solution produced.
  • A.   0.00100 mol/dm3   
  • B.   0.0160 mol/dm3   
  • C.   1.00 mol/dm3       
  • D.   16.0 mol/dm3
6. Hydrobromic acid can be neutralized using potassium hydroxide solution.

The equation for the reaction is:

HBr(aq) + KOH(aq) → KBr(aq)  + H2O

  
Calculate the volume of 0.20 mol/dm3 potassium hydroxide solution needed to exactly neutralize 0.0020 moles hydrobromic acid.
  • A.   0.010 cm3      
  • B.   1.0 cm3     
  • C.   0.010 dm3    
  • D.   10 dm3

Q7-10.
A chemist carries out a titration to find the concentration of a solution of sodium hydroxide.


She titrates 25.0cm3 of sodium hydroxide solution with a solution of sulfuric acid using phenolphthalein as an indicator.  

14.6cm3 of 0.200mol/dm3 sulfuric acid was required.

 acid + base titration
H Padleckas
CC BY-SA 4.0

The equation for the reaction is:

2NaOH(aq) + H2SO4(aq)  →  Na2SO4(aq) + 2H2O(l)

7. The most suitable pieces of apparatus for measuring the volumes of sodium hydroxide and sulfuric acid are: 

  Sodium hydroxide volume Sulfuric acid volume
A burette pipette
B pipette burette
C Measuring cylinder burette
D Measuring cylinder Measuring cylinder
8. The amount, in moles, of sulfuric acid used in this titration is:
  • A.   0.00500      
  • B.   5.00         
  • C.   0.00292      
  • D.   2.92
9. The amount, in moles, of sodium hydroxide used to neutralize the sulfuric acid is:
  • A.   0.00292            
  • B.   0.00584         
  • C.   0.00146     
  • D.   5.84
10. The concentration, in mol/dm3, of the sodium hydroxide solution used to neutralize this sulfuric acid is:
  • A.   0.234 mol/dm3         
  • B.   0.117 mol/dm3        
  • C.   0.0584 mol/dm3     
  • D.   0.400 mol/dm3