# chemistry

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1.) How much ethanol, C2H5OH, in liters (d=0.789g/ml) must be dissolved in water to produce 190.5 of 1.65 M C2H5OH? (Molarity problem.)

2.) How much concentrated hydrochloric acid solution (36.0% HCl by mass, d = 1.18g/mL}), in milliliters, is required to produce 11.0 L of 0.296 M HCl?

• chemistry - ,

1.) How much ethanol, C2H5OH, in liters (d=0.789g/ml) must be dissolved in water to produce 190.5 of 1.65 M C2H5OH? (Molarity problem.)

190.5 WHAT for crying out loud?barrels, freight cars, lakes, I will assume you meant mL. If not that, adjust values below to what you should have written.
M = moles/L and moles = grams/molar mass.

1.65M = moles/0.1905. Calculate moles.
moles = gram/molar mass.
You know moles and molar mass, calculate grams.
From the density, calculate volume of ethanol to use and convert to liters.

• chemistry - ,

molarity=mass/molmass*volumeinLiters

1) massEthanol=density*volumeEthanol

so volumeEthanol=molarity*molmass*Volumesolution/density

Watch units.

2)work out the similar steps for the HCL.

• chemistry - ,

2.) How much concentrated hydrochloric acid solution (36.0% HCl by mass, d = 1.18g/mL}), in milliliters, is required to produce 11.0 L of 0.296 M HCl?

First calculate the molarity of the concentrated HCl.
1.18 g/mL x 1000 mL - mass of 1 L = 1180 g.
How much of that is HCl? 36% so,
1180 x 0.36 = 424.8 g HCl.
How many moles is that?
424.8/36.5 = 11.6 M
Now use the dilution formula to determine what you want to prepare.
mL x M = mL x M
Check my work. I estimated the molar masses and rounded here and there so you need to go through the problem yourself and do those numbers right.

• chemistry - ,

The second one is correct. Regarding the first one though, I calculated the grams to 6.8 g of C2H5OH. I don't quite understand the next step (regarding the density, etc)

• chemistry - ,

that was me who posted the comment above. my friend had the same question.

• chemistry - ,

I don't know how you obtained 6.8 g.