# The use of ice water in an experiment

An experiment from Vogel that I want to conduct requires "a mixture of ice and salt of about -10 °C". Reading trough the text it appears that I need at least 1-2 liters of this. Obviously the salt is added to lower the freezing point of the water. I guess the interaction of water with the dissolved salt trough hydrogen bonding / lone pair donation is more favorable (less energetic) than ordinary water-water interaction.

1. With "salt", does Vogel mean just $\ce{NaCl}$?

2. Since I'm a hobby chemist I do not have the same fancy machinery as they have in the lab (those cool things that generate rough ice shards and in which everybody stuffs food against all safety regulations lol). All I can use is a small refrigerator with a tiny freezer. It's easy enough to make some ice cubes, but how do I go about making these ice shards that are used in the lab? I don't think grinding the cubes is very practical as it is a tedious job that takes a lot of time in which the shards have probably already melted (also from hitting them with a pestle continuously)...

1.With "salt", does Vogel mean just $\ce{NaCl}$?

Yep, it's cheap and available.

1. How do I go about making these ice shards that are used in the lab?

Wrap the ice cubes in a towel and hit the bundle with a hammer until you get whatever size you want. That's how we did it in the lab.

• I was imagining myself using a pestle and mortar to crush all the cubes, a towel is much more practical indeed. Thanks for the very helpful tip (it is the stuff that is so simple yet is in no book!) Was my comment about why salt is used correct? – Jori Dec 29 '14 at 18:02
• Your welcome. As to why the addition of a salt to water leads to a freezing point depression, it has more to do with concentrations and chemical potential. See here, for example – ron Dec 29 '14 at 18:11