The enthalpy is the heat added to or lost in a system.
Answer:- 3.68M.
Solution:- We have a 22.0% by mass solution of ethylene glycol and it's density is 1.04 gram per mL. It ask to calculate the molarity of the solution. We know that molarity is moles of solute per liter of solution. So, we need to figure out the moles of ethylene glycol and volume of solution.
Let's say we have 100 grams of the solution. Then mass of ethylene glycol would be 22.0 grams. Molar mass of ethylene glycol is 62.07 gram per mol.
Let's calculate it's moles first:
= 
From mass and density we calculate the volume of the solution and convert it to liters as:
= 0.0962 L
= 3.68M
So, the molarity of ethylene glycol solution is 3.68M.
The radon-222 sample has a half-life of 3.8 days, and we are asked how many times would the mass divide in half after 23 days. First we calculate the amount of times division occurs by taking the number of days and dividing that by the number of days for one half-life to occur: 23/3.8 = 6.05.
We have 198.6 grams of sample, and we are going to divide it in half 6 times to determine how much of it remains after 23 days:
198.6/2 = 99.3 grams
99.3/2 = 49.65 grams
49.65/2 = 24.83 grams
24.83/2 = 12.41 grams
12.41/2 = 6.21 grams
6.21/2 = 3.1 grams
Therefore, we are left with 3.1 grams of radon-222 after 23 days if one half-life equals to 3.8 days.
Every redox reaction consists of two parts, the oxidation and the reduction. Each one separately is called a half - reaction. During the redox reaction there is a transfer of electrons from the substance being oxidized to the substance being reduced.
