Question

6. Jack is a student in CHEM 1211L and he just solved old him that he made a mistake. Can you point out where Jack mau question? (10 points) Just solved two dimensional analysis problems. His instructor t where Jack made mistakes and help him solve each (a) Jack was calcu Jack was calculating the mass in kol of 750.0 ml mercury, given the density Ormer (inexact, at 25°C). This is his work: 1.0 ml mercury, given the density of mercury 13.5 g/mL 750.0 mL Hg 1954 1 ml x 1 kg = 0.0556 kg Hg(1) 13.5 1000 g Analyze/explain what the mistake in Jack's solution is. (b) To help Jack you will write your solutions below. Show all details and unit factors. (c) Jack bought 1 pound (454 g) of dry ice from a grocery store. He tried to find out how many moles of oxygen atoms were contained in the solid sample. Below is his work: Molar mass of CO2: 1x12.010 g/mol + 2 x16.00 O g/mol = 44,01 g/mol 454 g CO2(s) mol 44.01 g 01. x 1 mol = 5.16 mol O 2 mol CO2 Which step (part) did he make a mistake? Why? (d) Solve the moles of oxygen properly:

Answer 1

(a) the mistake made by Jack is that he has divided volume by density in order to find mass, whereas the right approach would be : Mass = Volume * Density

(b) Mass = 750 mL * 13.5 g / mL * 1 kg / 1000 g = 10.125 kg

c) The mistake jack has made is that h has used 1 mol O per 2 mol CO₂ while it is actually 2 mol O per 1 mol CO₂

(d) Moles of O = 454 g CO₂ * 1 mol / 44 g / mol * 2 mol O / 1 mol CO₂ = 20.637 mol