How do you calculate the mass of NaCl required to prepare 0.5 liters of a 2.5 molar solution of NaCl?

Answer 1

Here's how you can do that.

The definition of molarity will be your starting point in this situation.

As you know, molarity is defined as the number of moles of solute present in exactly #"1 L"# of solution. This implies that a #"1-M"# solution will contain #1# mole of solute in #"1 L"# of solution.
In your case, a #"2.5-M"# solution will contain #2.5# moles of sodium chloride, your solute, for every #"1 L"# of solution. It follows that this sample must contain
#0.5 color(red)(cancel(color(black)("L solution"))) * overbrace("2.5 moles NaCl"/(1color(red)(cancel(color(black)("L solution")))))^(color(blue)("required molarity")) = "1.25 moles NaCl"#
Now, to convert this to grams of sodium chloride, you must use the mass of #1# mole of this compound as a conversion factor. The mass of #1# mole of sodium chloride is given by its molar mass
#1.25 color(red)(cancel(color(black)("moles NaCl"))) * "58.44 g"/(1color(red)(cancel(color(black)("mole NaCl")))) = color(darkgreen)(ul(color(black)("73 g")))#

You have one significant figure for the volume of the solution, so I'll leave the answer rounded to two sig figs.

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Answer 2

Mass (g) = Molarity (mol/L) × Volume (L) × Molar Mass (g/mol) Mass of NaCl = 2.5 mol/L × 0.5 L × 58.44 g/mol

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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