Am I crazy or is this an error? What am I missing here?
FL 8, PS #13
A student dissolved 20mg of solid sodium hydroxide in 30ml of distilled water. 50 mL of an unknown concentration of acetic acid (Ka = 1.8 x 10^-5) was required to completely neutralize the base present. What is the concentration of the added acetic acid?
I get how to do it until a certain part. The solution says that at the equivalence point, the conc. of acid added = the conc. of base there was. so In finding how many mols of base we had originally, you take the grams added (20mg= .02g) and divide that by the molar mass right? The molar mass is 40. so I do .02/40...
they say "its molar weight is 40mg/mmol, thus the number of moles acetic acid is equal to 20/40." I am not familiar with working with mmols and instinctively convert to moles, but I am not sure why this isn't working out to be the same.
FL 8, PS #13
A student dissolved 20mg of solid sodium hydroxide in 30ml of distilled water. 50 mL of an unknown concentration of acetic acid (Ka = 1.8 x 10^-5) was required to completely neutralize the base present. What is the concentration of the added acetic acid?
I get how to do it until a certain part. The solution says that at the equivalence point, the conc. of acid added = the conc. of base there was. so In finding how many mols of base we had originally, you take the grams added (20mg= .02g) and divide that by the molar mass right? The molar mass is 40. so I do .02/40...
they say "its molar weight is 40mg/mmol, thus the number of moles acetic acid is equal to 20/40." I am not familiar with working with mmols and instinctively convert to moles, but I am not sure why this isn't working out to be the same.
