PLEASE SHOW HOW YOU GOT EACH ANSWER! for questions 1-4 you have been provided wi

Question

PLEASE SHOW HOW YOU GOT EACH ANSWER!

for questions 1-4 you have been provided with 1.000 L of a 1.000 M stock solution of sucrose.

1) 100.0 mL of the stock is pipetted into a 1 L volumetric flask. What is the concentration of the 100.0 mL of sucrose solution that was just transferred to the volumetric?

2)How many moles of sucrose are contained within the 100.0 mL that was transferred into the volumetric?

3)If the 1 L volumetric is filled with enough DI water to make the volume of solution 1 L (referred to as being "brought to volume"), what will the new concentration of sucrose be?

4) If a soluition that is 1 M is diluted to 0.5 M its concentration is said to have dropped by a factor of 2 (2x less concentrated). If a solution that is 5 M is diluted to 1 M its concentration is said to have dropped by a factor of 5 (5x less concentrated). What factor has the concentration of the stock solution in question 3 above dropped by in making this new solution?

Explanation / Answer

1) The molarity given states that you have 1 mole of sucrose for every 1 liter of fluid volume. Since the moles are essentially evenly distributed, removing a tenth of that (100 mL) will also remove a tenth of the total moles. (.1 moles/.1 Liters = 1.00 M) Therefore, the 100.0 mL of sucrose solution transferred to the volumetric is still 1.000 M

2) Again, the moles were evenly distributed in the initial sample and removing a tenth of the volume also removed a tenth of the total moles present. .1 moles over .1 Liters (100 mL) yields a 1 Molar solution. Therefore .1 moles was transfered.

3) You begin with 100 mL (.1L) with .1 moles in solution. To bring the flask up to volume you will add 900 mL (.9L) so that the total volume is 1 Liter. To find the concentration you divide the number of moles present ( .1 ) by the volume ( 1 L) which yields a concentration of .1 M

4) Dividing the initial concentration of 1 M by the final concentration of .1 M gives you a factor of 10.

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