Question

SHOW HOW YOU GOT THE ANSWER FOR PROBLEMS 1-5

Question 1

Which is the correct explanation of how you would make 450ml of a 0.250M solution of NaOH solution.

Add 4.52 grams of NaOH until the final volume of the solution is 450ml

Add 45.2 grams of NaOH until the final volume of the solution is 450ml

Add 250 grams of NaOH until the final volume of the solution is 45.0ml

Add 45.2 grams of NaOH until the final volume of the solution is 500ml

SHOW WORK PLEASE

Question 2

To what volume will you have to dilute 30ml of 12M HCl solution to make a 0.35M HCl solution?

1000ml

1300ml

1030ml

1500ml

SHOW WORK PLEASE

Question 3

How many grams of calcium chloride will be needed to make 750ml of a 0.100M CaCl2 solution?

83grams

54.3grams

83.3grams

8.33grams

SHOW WORK PLEASE

Question 4

53.4ml of a 1.50M solution of NaCl is on hand, but you need some 0.800M solution. How many ml of 0.800M solution.

10ml

0.10ml

100ml

150ml

SHOW WORK PLEASE

Question 5

100.0ml of 2.500M KBR solution is on hand. You need 0.5500M. What is the final volume of solution which results?

454.5mL

545.0mL

400.5mL

452.0mL

SHOW WORK PLEASE

Answer 1

1. 450 ml of 0.250M solution will have 0.250/1000X450 moles of NaOH = 0.1125 moles of NaOH present in it.

0.1125 moles NaOH = 0.1125X40 gm NaOH ( molecular weight of NaOH is 40) = 4.5 gm NaOH

Ans. Option 1 Add 4.52 gm of NaOH untill the final volume is 450 ml

2. 30 ml of 12M solution of HCl= 12/1000X30 moles of HCl= 0.36 moles of HCL.

Now the final concentration needs to be 0.35M which means 0.35 moles in 1000 ml solution.

So 0.35 moles in 1000 ml produces 0.35M solution

Therefore 0.36 moles in 1000/0.35X0.36 ml = 1028 ml produces 0.35M solution

Ans: Option 3- 1030ml

3. 750 ml of 0.100M CaCl2 = 0.100/1000X750 moles of CaCl2= 0.075 moles of CaCl2= 0.075X111 gm CaCl2(molar mass of CaCl2=111gm) = 8.325 gm CaCl2 needs to be added.

Ans: Option 4- 8.33 gm CaCl2 needs to be added

4. 53.4 ml of 1.50M NaCl= 1.50/1000X53.4 moles of NaCl= 0.0801 moles of NaCl

Therefore to make 0.800M NaCl the final volume of the solution needs to be 1000/0.800X0.0801 ml= 100.125 ml

Ans:Option 3 100 ml

5. V1S1=V2S2

V1,V2- Initial and final volume

S1 , S2- Initial and final strength

2.5X100=0.55XV2

V2= 2.5X100/0.55 ml= 454.5 ml

Ans Option 1