Grayson asked in Science & MathematicsChemistry · 3 weeks ago

# To obtain the solute for 205 g of a 18.7% (w/w) solution of sugar we would weigh out ________ g of sugar.?

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• 3 weeks ago

18.7% =( weight of solute/(weight of solute+weight of solvent))*100

18.7/100 = ( weight of solute/(weight of solute+weight of solvent))

0.187 = ( weight of solute/(weight of solute+weight of solvent))

0.187 = weight of solute / 205g

∴ weight of solute = 0.187*205g

= 38.335g

• 3 weeks ago

18.7% of the 205g is sugar

205 * 18.7 / 100 =>

205 * 187 / 1000

205 * 187 =>

(200 + 5) * (200 - 13) =>

200^2 + 5 * 200 - 13 * 200 - 65 =>

40,000 + 200 * (5 - 13) - 65 =>

40,000 + 200 * (-8) - 65 =>

40,000 - 1600 - 65 =>

38,400 - 65 =>

38,335

38335 / 1000 =>

38.335

to 3 sf

38.3 grams

205 - 38.3 =>

205 - 40 + 1.7 =>

165 + 1.7 =>

166.7

Conservation of mass says that the mass that goes in will be the mass that comes out.  Mixing 38.3 grams of sugar with 166.7 grams of water will give you 205 grams of solution that is 18.7% sugar by weight.