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# Is my textbook inaccurate? watch

1. An example question in my book seems to be wrong:

What is the mass of sodium hydroxide in 100cm^3 of a solution with a concentration of 0.2 mol/dm^3?

100cm^3 contains 100 x 0.2/1000 mol = 0.02 mol
1 mol NaOH = 40g; therefore 0.02mol has a mass of 0.02 x 40 = 8g

-----------------

However, when I did the calculation myself, I got 0.8g. I'm sure the book is wrong?
2. If you work it backwards and start with 8 g, you get 0.2 mol, which when dissolved into 100 cm3 makes a 2 mol dm-3 solution. The book is wrong.

The book states that 0.02 x 40 = 8 g, when in fact it makes 0.8 g.

You're correct.
3. (Original post by Pigster)
If you work it backwards and start with 8 g, you get 0.2 mol, which when dissolved into 100 cm3 makes a 2 mol dm-3 solution. The book is wrong.

The book states that 0.02 x 40 = 8 g, when in fact it makes 0.8 g.

You're correct.
Thank you very much! I'm sure I can probably compain to Nelson Thornes and get it fixed :P

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