How do I prepare a #"3 M"# #"NaOH"# aqueous solution?

1 Answer
Truong-Son N.
Aug 21, 2015

It depends on how accurate you want it. If you just want #"3.000 M"#, and you want to be practical:

#"NaOH: 39.9959 g/mol"#

Using a #"100.00-mL"# volumetric flask gives you two decimal places of accuracy and is not that wasteful.

#cancel("100.00 mL") * ((3.000 cancel("mol"))/(cancel("1000" "mL")))("39.9959 g"/(1 cancel("mol")))#

#=# #"11.9988 g"# #-># #"12.00 g"# to four sig figs.

which is a reasonable amount to measure out in lab. If you want to use #"12.00 g"# because it's easier, that gives you:

#("12.00 g"/"39.9959 g/mol")/(100.00 cancel"mL" xx "1 L"/(1000 cancel"mL")) = "3.000 M"#

(So you don't even need a scale that measures out to 4 decimal places.)

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