Chem molarity q (1 Viewer)
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ppm is mg/L
2.0 ppm = 2.0 mg/L of Pb2+
2.0 mg/ L x 1.0 L = 2.0 mg of Pb2+
find the moles of Pb2+
that equals moles of Pb(NO3)2
multiply that by molecular mass of Pb(NO3)2 to find the mass of Pb(NO3)2
2.0 ppm = 2.0 mg/L of Pb2+
2.0 mg/ L x 1.0 L = 2.0 mg of Pb2+
find the moles of Pb2+
that equals moles of Pb(NO3)2
multiply that by molecular mass of Pb(NO3)2 to find the mass of Pb(NO3)2
i get 0.00159 grams but the answer is 1.6, i divided 2mg by 1000 to get it into grams and workout the amount of moles of pb since m in the formula is in grams,
m(Pb2+) = 2.0 mg = 2 x 10^-3 g
n(Pb2+) = m/MM = (2x10^-3) / 207.2
n(Pb2+) = 0.0000096525 moles
n(Pb(NO3)2) = n(Pb2+)
n(Pb(NO3)2) = 0.0000096525 moles
m(Pb(NO3)2) = nMM = 0.0000096525 x (207.2 + 2(14.01 + 3x16)) = 0.00319... g
Neither your or the textbook answer is correct
This is mostly a memorise the formula and sub kind of question
% means fraction x 100
W/v tells you what to put on the top and bottom of the fraction
%w/v = mass / volume x 100
Sub the 1.5% and volume as 25 for Ethanol and solve for mass
ohh got it thanks