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C ezto.mheducation.com/hm.tpx Econnect Mr. Novak\'s Honors Chemistry-Periods #2

ID: 1034657 • Letter: C

Question

C ezto.mheducation.com/hm.tpx Econnect Mr. Novak's Honors Chemistry-Periods #2 & #6: 2017-2108-Period #2 & # 6 Hon Hannah Miller TEST Chapter r2 . Sections st21 to #12.8 all pue: wed. 03/07/2018 0 1030 pm) Question 20 jof 20) 20 10.00 points Question Be sure to answer all parts. Assistance Caloulate the amount of water (in grams) that must be added to each of the following substances to produce the indicated solution. (a) 4.30 g of urea (NH2)2 CO in the preparation of a 14.1 percent by mass solution: (b) 35.3 g of MgCl2 in the preparation of a 7.3 percent mass solution:

Explanation / Answer

(a)

% by mass of urea = mass of urea * 100 / total mass of mixture

14.1 = 4.30 * 100 / (4.30 + mass of water)

4.30 + mass of water = 430 / 14.1

4.30 + mass of water = 30.5

Mass of water = 34.8 g.

(b)

Similar to the above,

7.3 = 35.3 * 100 / (35.3 + mass of water)

35.3 + mass of water = 3530 / 7.3

Mass of water = 483.6 - 35.3

Mass of water = 448.3 g.