You have 2.5L of .14M salt solution, how many grams of salt would be needed to make this solution?

Question

Owen Ambrose · Accepted Answer

#"20. g"#

The thing to recognize here is that the molarity of the solution tells you the number of moles of solute present in exactly #"1 L"# of this solution.

In your case, the solution is said to have a molarity of #"0.14 M"#, which implies that every #"1 L"# of this solution contains #0.14# moles of salt, the solute.

Now, in order to have #"2.5 L"# of #"0.14 M"# salt solution, you need the solution to contain

#2.5 color(red)(cancel(color(black)("L solution"))) * "0.14 moles salt"/(1color(red)(cancel(color(black)("L solution")))) = "0.35 moles salt"#

In order to find the number of grams needed to have #0.35# moles of salt, you need to use the compound's molar mass. Assuming that the salt is table salt, or sodium chloride, #"NaCl"#, you will have

#0.35 color(red)(cancel(color(black)("moles NaCl"))) * "58.4 g"/(1color(red)(cancel(color(black)("mole NaCl")))) = color(darkgreen)(ul(color(black)("20. g")))#

The answer must be rounded to two sig figs, the number of sig figs you have for your values.

Owen Ambrose · Answer

undefined To calculate the grams of salt needed to make the solution, you can use the formula:

$ \text{grams of salt} = \text{volume of solution} \times \text{molarity} \times \text{molar mass of salt} $

Given:
Volume of solution = 2.5 L
Molarity of solution = 0.14 M

The molar mass of salt depends on the specific salt being used. Assuming you are referring to table salt (NaCl), the molar mass is approximately 58.44 g/mol.

Using the formula:

$ \text{grams of salt} = 2.5 \, \text{L} \times 0.14 \, \text{mol/L} \times 58.44 \, \text{g/mol} $

$ \text{grams of salt} = 20.46 \, \text{g} $

So, approximately 20.46 grams of salt would be needed to make this solution.