How many grams of na2s do we need to dissolve in 200ml of water to get a solution that is 0.2 m?

We know that the molarity of a solution is calculated by the following equation:



That being said we are given two of the 3 things that we need: Volume of water, as well as the molarity of the solution. Let's plug those in to the equation to find how many moles of  that we need:

=>

This means that we have 0.04 moles of .

In order to calculate the number of grams that we need for this solution, we must first calculate how many grams of are in 1 mole. We do this by taking the atomic masses of each element from the periodic table and adding them together.

Na = 22.99 g
S = 32.06 g

We have 2 Na's, and we have 1 S. So lets add them together:

2(22.99) + (32.06) = .

Since we need 0.04 moles of , we can multiply the molar weight of the molecule times the amount of moles needed to find the total grams that we need for the solution:



Now we know that in order to make a 0.2 M solution of , we must use 3.1216 grams.

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.