How can water have a molarity if theres no diff b/w solute and solvent?

jenzao

mental block about this please help.
molarity is mols or a substance per Liter of a solution right?
that is, mols of the solute in litres of solution.

1. What is the solution?
2. if its water, then how can you say water has a molarity?

Borek

Don't think in terms of solution - ie separate solvent and solute. Concentration is just amount per liter, not per liter of water. Thus you have 55.55 moles of water per liter.

gravenewworld

Because molarity is how much stuff you have in a certain amount of volume. It doesn't matter if it is water or an HCl solution.

jenzao

So that means that compounds dont necessarily have set molarities right?
for ex, H20 always has mass of 16 + 1 + 1 = 18, and 1 mole is always 18g, but its molarity depends on how many liters of volume 1 mole is contaained in, is that right?

If yes, then why is water said to be 55.5M ??

Redbelly98

Not quite. Molarity is how many moles are in 1 liter. For water, it happens to be 55.6. 1 liter of water contains 55.6 moles of water.

Borek

To be exact, molarity of pure water is 1000/18.02 = 55.51

However, in the 1M solution of acetic acid there is only 946.9 g of water per liter, so its molarity in such solution will be 846.85/18.02 = 52.56

harish8u

molarity=no.of moles per volume of soluton in liters
but u did 1000/18.02 how?

Borek

What is mass of 1L of water?

How many moles in that mass?

--
chemical calculators - buffer calculator, concentration calculator
www.titrations.info - all about titration methods

emiliostar

Let me breakdown:
Re: (1L = 1000 cm^3)
water has an approximate density of 1g/cm^3 (temperature dependent)
Therefore, 1000 cm of pure water has an approximate mass of 1000g
Mass of 1 mole of water = 18.02 g
Hence, no. of moles water in 1000 cm^3 of water = Total mass/mass of 1 mole = 1000 g/18.02g per mole = 55.55 moles