Why is salt water more dense than fresh water and sugar water?

Answer 1

Salt and sugar both dissolve in water, thereby increasing its mass. Salt is approximately 40% more dense than sugar, and thereby the salt water is more dense than sugar water (when either are added in the same quantities by volume).

Answer 2

If you get a measuring jug and fill it with fresh water up to the one litre line, you have a fixed volume of water - a litre - with a density of 1.

Now add 100 grams of table salt to the water and stir it until it is all dissolved.

You will notice that despite the addition of the salt, the volume in the jug will still measure one litre.

However, the salty water will now weigh 100 grams more than the fresh water did but it still occupies the same volume. Thus its density will now be greater than 1.

What is happening is that the components that make up the salt (NaCl) when dissolved in the water, sort of fit into the natural spaces between the water molecules and thus the solution does not need to take up more room it is just more dense (there is more stuff in the same space).

Answer 3

AnswerBefore answering this question, we must be familiar with the word 'density' and 'solubility'. Density is the mass per unit volume. Salt and sugar both can increase the density of water. Solubility is the amount of a solid that can be dissolved in a liquid.

While the density of table salt (2160 g/L) is larger than sucrose (common sugar) (1590 g/L), salt has a much lower solubility (360 g/L) than sugar (2000 g/L). By those solubility numbers, salt-water can be as dense as 930 g/L ( (360g salt + 1000g water )/(1L water + 1/2.16 L salt) ) but sugar-water can be as dense as 1842 g/L ( (2000g sugar + 1000g water )/(1L water + 1/1.59 L sugar) ).

Therefore, adding salt increases the mass more quickly than adding the sugar, if you are measuring them by volume. However, water can be made heavier (as a maximum) with sugar.

^^

Sorry but this answer is totally wrong (apologies). what you have done is mathematically horrible. But think of it like this - salt water is effectively the sea - and the density of sea water is higher than pure water.....