Chemistry - Concentration Terms Question with Solution | TestHub

Solution:

We need to find which option contains 46g of HCOOH. The molar mass of HCOOH is $12.01+2\times 1.008+2\times 16.00=46.02g/mol$.

Option A: 92 g of 70% w/v HCOOH ($d_{solution}=1.4g/mL$)

The percentage w/v is given as 70%. This means 70 g of HCOOH per 100 mL of solution.

Mass of HCOOH = (70 g HCOOH / 100 mL solution) * Volume of solution

First, find the volume of the 92 g solution:

Volume of solution = Mass / Density = $92\mathrm{g}/1.4g/mL=65.71\mathrm{mL}$

Mass of HCOOH = $(70/100)\times 65.71\mathrm{mL}=46\mathrm{g}$

So, option A is correct.

Option B: 100 g of 10 M HCOOH ($d_{solution}=1g/mL$)

First, find the volume of the 100 g solution:

Volume of solution = Mass / Density = $100\mathrm{g}/1g/mL=100\mathrm{mL}=0.1\mathrm{L}$

Moles of HCOOH = Molarity $\times$ Volume = $10mol/L\times 0.1\mathrm{L}=1\mathrm{mol}$

Mass of HCOOH = Moles $\times$ Molar Mass = $1\mathrm{mol}\times 46.02g/mol=46.02\mathrm{g}$ (approximately 46 g)

So, option B is correct.

Option C: 100 g of 25% w/w HCOOH

Mass of HCOOH = $(25/100)\times 100\mathrm{g}=25\mathrm{g}$

So, option C is incorrect.

Option D: 92 g of 5 M HCOOH ($d_{solution}=1g/mL$)

First, find the volume of the 92 g solution:

Volume of solution = Mass / Density = $92\mathrm{g}/1g/mL=92\mathrm{mL}=0.092\mathrm{L}$

Moles of HCOOH = Molarity $\times$ Volume = $5mol/L\times 0.092\mathrm{L}=0.46\mathrm{mol}$

Mass of HCOOH = Moles $\times$ Molar Mass = $0.46\mathrm{mol}\times 46.02g/mol=21.17\mathrm{g}$

So, option D is incorrect.

The final answer is $\boxed{A,B}$.