What is the molar concentration of the solution after adding 1 mL of 6.00 mol/L #"HCl"# to 499 mL of water?

1 Answer
Aug 14, 2016

Answer:

The molar concentration of the dilute #"HCl"# solution is 0.0120 mol/L.

Explanation:

The critical thing to remember is that

#"moles of HCl before dilution = moles of HCl after dilution"#

The formula for molar concentration #c# is

#color(blue)(bar(ul(|color(white)(a/a)c = "moles"/"litres"color(white)(a/a)|)))" "# or #color(blue)(bar(ul(|color(white)(a/a)c = n/Vcolor(white)(a/a)|)))" "#

Moles of #"HCl"# in 1 mL

#n = "0.001 00" color(red)(cancel(color(black)("L HCl"))) × "6.00 mol HCl"/(1 color(red)(cancel(color(black)("L HCl")))) = "0.006 00 mol HCl"#

Molar concentration of the dilute #"HCl"#

There will still be 0.006 00 mol of #"HCl"# after you have added 499 mL of water.

#c = n/V = "0.006 00 mol"/"0.500 L" = "0.0120 mol/L"#