So in science we are doing cold packs,
So we have to use water and the following....
Please help me choose one(have to get from 0 degrees to 5 degrees no higher no less or you will fail)
1. Urea
2. Potassium Chloride
3. Ammonium Chloride
4. Sodium Chloride
http://webserver.dmt.upm.es/~isidoro/dat1/Heat%20of%20solution%20data.pdf
I am puzzled: you mentioned "cold packs", which absorb heat going into solution, which would indicate going from 5 deg to 0 deg.
I'm not sure I understand your question but if you have heard of hot packets(a packet you shake and gets warm) It's like that but the object of the investigation is to make it cold not warm. Sorry if it dosen't answer your confusion
To determine which substance will help you achieve the desired temperature range, we need to understand the concept of freezing point depression. Freezing point depression occurs when the addition of a solute lowers the freezing point of a solvent. In this case, the solvent is water, and the solute is one of the substances listed.
To determine which substance will be most effective, we need to compare their freezing point depression properties. The greater the decrease in freezing point, the more effective the substance will be in achieving the desired temperature range.
First, we need to determine the freezing point of water. The freezing point of pure water is 0 degrees Celsius (32 degrees Fahrenheit).
Urea (Choice 1): The freezing point depression constant for urea is about -1.86 degrees Celsius/mole. This means that for every mole of urea dissolved in one kilogram of water, the freezing point will decrease by 1.86 degrees Celsius. To achieve a 5 degrees Celsius decrease, you would need to calculate how many moles of urea you would need.
Potassium Chloride (Choice 2): The freezing point depression constant for potassium chloride is about -1.98 degrees Celsius/mole. This means that for every mole of potassium chloride dissolved in one kilogram of water, the freezing point will decrease by 1.98 degrees Celsius. Again, you would need to calculate how many moles of potassium chloride are needed for a 5 degrees Celsius decrease.
Ammonium Chloride (Choice 3): The freezing point depression constant for ammonium chloride is about -3.33 degrees Celsius/mole. This means that for every mole of ammonium chloride dissolved in one kilogram of water, the freezing point will decrease by 3.33 degrees Celsius. Calculate the number of moles required to achieve a 5 degrees Celsius decrease.
Sodium Chloride (Choice 4): The freezing point depression constant for sodium chloride is about -1.86 degrees Celsius/mole. This means that for every mole of sodium chloride dissolved in one kilogram of water, the freezing point will decrease by 1.86 degrees Celsius. Calculate the number of moles needed for a 5 degrees Celsius decrease.
By comparing the freezing point depression constants, you can determine which substance will require the fewest moles to achieve the desired temperature decrease of 5 degrees Celsius. Remember to consider the molar mass and ensure that you do not exceed the maximum specified temperature, as it may result in failure.