MCQ Solution: Solutions
10 mL of 2(M)NaOH solution is added to 200mL of 0.5(M) of NaOH solution. What is the final concentration?
1) 0.3 M
2) 0.6 M
3) 0.5 M
4) 0.4 M
Solution
Number of moles of NaOH in 10 mL of 2 M solution
=(10 mL / 1000 mL/L)×2 mol/L=0.02 mol
Number of moles of NaOH in 200 mL of 0.5 M solution
=(200 mL / 1000 mL/L) × 0.5mol/L=0.1 mol
Total number of moles of NaOH=0.02+0.1=0.12 mol
Total volume =10+200=210 mL =0.210 L
Final concentration =0.210 L / 0.12 mol = 0.57 M
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