Question #72f34

2 Answers
Dec 10, 2017

[HCl]~=0.065*mol*L^-1[HCl]0.065molL1

Explanation:

We first write the stoichiometric equation....

HCl(aq) + KOH(aq) rarr KCl(aq) +H_2O(l)HCl(aq)+KOH(aq)KCl(aq)+H2O(l)

...to establish the 1:1 equivalence...

And thus [HCl]=(25.81*mLxx10^-3*L*mL^-1xx0.1250*mol*L^-1)/(50.00xx10^-3*L)[HCl]=25.81mL×103LmL1×0.1250molL150.00×103L

=0.06453*mol*L^-1=0.06453molL1

Dec 10, 2017

"0.065 M"0.065 M

Explanation:

The formula for the reaction is

"HCl" + "KOH" -> "KCl" + "H"_2"O"HCl+KOHKCl+H2O

and its already balanced (yea!).

When the mL and M of something ("KOH")(KOH) is givenm use cross multiplication to find how many mols (remember "M"M is "mol/liter"mol/liter, or "mol/1000 mL"mol/1000 mL):

"0.1250 mol"/"1000 mL" = "x mol"/ "25.81 mL"0.1250 mol1000 mL=x mol25.81 mL

to get 3.23xx10^-33.23×103 "moles KOH"moles KOH, and since in the reaction equation all coefficients are 1, that means there were 3.23xx10^-33.23×103 "moles"moles of "HCl"HCl in the "50 mL"50 mL sample.

Then, you use cross multiplication again to find how many moles would be in "1000 mL"1000 mL of that sample:

"x mol"/"1000 mL" = (3.23xx10^-3 "mol")/ "50 mL"x mol1000 mL=3.23×103mol50 mL

which will give you "0.065 mol/1000 mL"0.065 mol/1000 mL, which is "0.065 M"0.065 M.