How many moles of NaOH are present in 19.0 mL of 0.150 M NaOH?

1 Answer
Nov 7, 2015

Answer:

#"0.00285 moles"#

Explanation:

Molarity is defined as moles of solute, which in your case is sodium hydroxide, #"NaOH"#, divided by liters of solution.

#color(blue)("molarity" = "moles of solute"/"liters of solution")#

SImply put, a #"1-M"# solution will have #1# mole of solute dissolved in #1# liter of solution.

Now, you know that your solution has a molarity of #"0.150 M"# and a volume of #"19.0 mL"#.

Since the volume is much smaller than #"1 L"#, you can expect to have fewer moles of sodium hydroxide in this sample than you would have had in a full liter of solution.

Convert the volume of the sample from mililiters to liters by using the conversion factor

#"1 L" = 10^3"mL"#

to get

#19.0color(red)(cancel(color(black)("mL"))) * "1 L"/(10^3color(red)(cancel(color(black)("mL")))) = 19.0 * 10^(-3)"L"#

This means that the number of moles of solute you get in this sample will be equal to

#color(blue)(c = n/V implies n = c * V)#

#n = 0.150"moles"/color(red)(cancel(color(black)("L"))) * 19.0 * 10^(-3)color(red)(cancel(color(black)("L"))) = color(green)("0.00285 moles NaOH")#