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1 vote
3. A volume of 90 mL of 0.2 M HBr neutralizes

a 60 mL sample of NaOH solution. What is
the concentration of the NaOH solution?

2 Answers

3 votes

Answer:


M_(NaOH)=0.3M

Step-by-step explanation:

Hello,

In this case, since we are talking about a neutralization reaction, the moles of acid must equal the moles of base as shown below:


n_(HBr)=n_(NaOH)

Thus, in terms of molarities we've got:


M_(HBr)V_(HBr)=M_(NaOH)V_(NaOH)

This is possible since HBr reacts with NaOH in a 1:1 molar ratio:


HBr+NaOH\rightarrow NaBr+H_2O

Hence, for the given concentration and volume of hydrobromic acid and the volume of sodium hydroxide, we compute its concentration as shown below:


M_(NaOH)=(M_(HBr)V_(HBr))/(V_(NaOH)) =(90mL*0.2M)/(60mL) \\\\M_(NaOH)=0.3M

Best regards.

User Nourish
by
4.1k points
2 votes

Answer:

0.3M

Step-by-step explanation:

Step 1:

Data obtained from the question. This include the followingb:

Volume of acid (Va) = 90mL

Concentration of acid (Ca) = 0.2M

Volume of base (Vb) = 60mL

Concentration of base (Cb) =....?

Step 2:

The balanced equation for the reaction. This is given below:

HBr + NaOH —> NaBr + H2O

From the balanced equation above,

The mole ratio of the acid (nA) = 1

The mole ratio of the base (nB) = 1

Step 3:

Determination of the concentration of the base, NaOH.

The concentration of the base can be obtained as follow:

CaVa /CbVb = nA/nB

0.2 x 90 / Cb x 60 = 1

Cross multiply

Cb x 60 = 0.2 x 90

Divide both side by 60

Cb = 0.2 x 90 /60

Cb = 0.3M

Therefore, the concentration of the base, NaOH is 0.3M

User Pavel Surmenok
by
2.8k points