GCHEM...Achiever..

[future_dentist]

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Please someone explain...Q#41 Achiever test #1....

How many milliliters of 3.0 M H2SO4 are required to neutralize 30.0 ml of 4.0 M NaOH?

A. 15
B. 20
C. 25
D. 30
E. 40

Ans: B (they say 0.5 mole of H2SO4 is required to neutralize every mole of NaOH)

How????? its 3moles H2SO4 not 2.....

Thanks

 

[Notoriousjae]

Please someone explain...Q#41 Achiever test #1....

How many milliliters of 3.0 M H2SO4 are required to neutralize 30.0 ml of 4.0 M NaOH?

A. 15
B. 20
C. 25
D. 30
E. 40

Ans: B (they say 0.5 mole of H2SO4 is required to neutralize every mole of NaOH)

How????? its 3moles H2SO4 not 2.....

Thanks

Use the normality concept.
because there are 2 equivalents of H+, the 3M/2=1.5. to convert to normality you do 3* 2=6N
so V * 6N= 30ml*4N
V=120/6=20mL

 

[future_dentist]

Use the normality concept.
because there are 2 equivalents of H+, the 3M/2=1.5. to convert to normality you do 3* 2=6N
so V * 6N= 30ml*4N
V=120/6=20mL

This may sound really stupid why Normality.....we have everything given to use this -----> M1V1=M2V2

Can u give me defination of Normality...

Really appreciate it....

And one more thing r freaking out about the test....

 

[joonkimdds]

This may sound really stupid why Normality.....we have everything given to use this -----> M1V1=M2V2

Can u give me defination of Normality...

Really appreciate it....

And one more thing r freaking out about the test....

Notoriousjae is a smart guy, he can't be freaking out about the test

 

[Notoriousjae]

This may sound really stupid why Normality.....we have everything given to use this -----> M1V1=M2V2

Can u give me defination of Normality...

Really appreciate it....

And one more thing r freaking out about the test....

you have to convert to normality because you have to take into account the 2 equivalents of H+ in H2SO4 that are transferred to neutralize the base. here are some links that should help you out. good luck. 🙂
Am i freaking out? um YES! i think anybody in the right frame of mind would be, although if you freak out too much, you tend to forget a lot of what you studied so that might not be a good thing.
http://environmentalchemistry.com/yogi/chemistry/MolarityMolalityNormality.html
http://www.carolina.com/chemistry/experiments/review.asp

joonkimdds, your sarcasm is greatly appreciated. 🙄

 

[future_dentist]

Thank u.....second link is great....

 

[DonExodus]

3M= (3mol H2SO4 / 1L)(2H+ / mol H2SO4) = 6 mol H+ / L
4M= (mol OH) / .03L = .12 mol OH-.

Neutralized when [OH]=[H]
6H/L = .6H/.1L = .06H/.01L . Gettin close, double that yields
.12H/.02L.

 

[KTDMD]

This may sound really stupid why Normality.....we have everything given to use this -----> M1V1=M2V2

Can u give me defination of Normality...

Really appreciate it....

And one more thing r freaking out about the test....

M1V1=M2V2 is usually used when diluting a reagent to the right amount of concentration in molarity, M for your lab experiment. To apply it here:

V2 = M1V1/V2 = (4.0 x 30.0) / 3.0 = 40.0 ml

(Note: The above equation is intended to conform the concentration of NaOH to the one of H2SO4.)

But you need only half the amount of H2SO4 to neutralize NaOH, hence the answer is 40.0/2 = 20.0 ml.