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Solutions and concentrationChemistryHigh schoolabout 0:47

25 mL of 2 M solution is diluted to 100 mL. What is the new concentration?: animated lesson

A narrated, step-by-step solutions and concentration video lesson with captions. Final answer: final concentration M₂ = 0.5 M.

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.3 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Worked example
25 mL of 2 M solution is diluted to 100 mL. What is the new concentration?
2. Step by step
1. $M_1V_1 = M_2V_2$
  Moles of solute stay the same when you dilute
2. $M_2 = \frac{M_1\,V_1}{V_2}$
  Rearrange for final concentration M₂
3. $M_2 = \frac{(2\ \text{M})(25\ \text{mL})}{100\ \text{mL}} = 0.5\ \text{M}$
  Substitute
3. The answer
$\text{final concentration M₂ = 0.5 M}$
final concentration M₂ = 0.5 M
4. Check
- M₁V₁ = 50 and M₂V₂ = 50 ✓

Transcript

The problem. Here is the problem: 25 mL of 2 M solution is diluted to 100 mL. What is the new concentration? Diluting adds solvent but not solute, so the moles of solute before and after are equal.

Step by step. Moles of solute stay the same when you dilute. Rearrange for final concentration M₂. Substitute.

The answer. So the answer is final concentration M₂ equals 0.5 M. Any volume unit works in M₁V₁ equals M₂V₂ as long as both volumes use the same one. Moles of solute: 0.05 mol.

Check. M₁V₁ equals 50 and M₂V₂ equals 50, which checks out.

About solutions and concentration

Molarity, dilution and moles of solute in a solution.

25 mL of 2 M solution is diluted to 100 mL. What is the…