Pre-Laboratory Assignment 2. A authoritative sources for discussion of glass wor
ID: 509543 • Letter: P
Question
Pre-Laboratory Assignment 2. A authoritative sources for discussion of glass working, of burets, of titration techniques. and ax student preparing to do this experiment fined the 150-mL beaker with a colorless liquid that was supposed be water. Later, the student feared that 10M Ha had been used instead of to Explain how the student could use a tiny piece of Mg to whether the solution in the was 1.0M HCI or water. What, contained HCI solution? If the beaker would the student observe the beaker contained water? (2) The CD is the ea her contoina HCI on voy the student that beaker HCI solution, which is toxic and corrosive. make the procedure the student could follow, using reagents available for this solution safe enough to be poured into drain, diluting with a large amount of running the 13) Describe any safety precautions the student should take carrying out the procedure mentioned in 2) in the following data. When 02158gof Zn reacted with 1000 mL of 1.000M HCI,82.062 gof water was displaced. A total of 3600 mL of 9.501 x 10 M NaoH solution was required to titrate the HCI remaining in the reaction mixture at the end of the reaction. The room temperature was270°C and the barometric pressure was 777 torr. The gram atomic mass of zn .The density of is 6538 g mol water at 270°Cis 0.9965 g mL and its vapor pressure is 270 torr. R-821 10 2Latm K 'mol Glint See Calculations) Calculate the volume of the displaced water from its mass. Notethat the volume of the water win be equal to the volume of the gas collected.Explanation / Answer
Experiment
2. If accidentally student used HCl in place of water
(1) Adding a piece of Mg, would produce H2 bubbles easily visible coming off the solution,
Mg + 2HCl --> MgCl2 + H2(g)
(2) Add dilute NaOH to the HCl solution to neutralize
NaOH neutralized HCl to form H2O. Dilute with sufficient water prior to neutralization reaction and disposing the chemicals.
(3) Wear proper safety clothing, gloves, safety goggles and carry the reaction in a well ventillated fume hood.
1) density of water = 0.9965 g/ml
Therefore,
Volume of water dispaced = mass of water/density of water
= 82.062 g/0.9965 g/ml
= 82.35 ml
Volume of H2 gas = Volume of water displaced
= 82.35 ml = 0.08235 L
2) Pressure of H2 collected = atmospheric pressure - water vapor partial pressure at the temperature of experiment
= (777 - 27) torr
= 750 torr/760 torr
= 0.987 atm
3) moles of H2 collected (n) = PV/RT
= pressure of H2(atm) x Volume of flask(L)/gas constant(L.atm/mol.K) x Temperature(K)
= 0.987 x 0.08235/0.0821 x (273 + 27)
= 0.0033 mol
4) moles of HCl originally present in the flask = molarity of HCl solution(M) x volume of HCl taken(L)
= 1.0 M x 0.01 L
= 0.01 mol
5) moles of HCl remained in the flask = Total moles of HCl added - moles of HCl reacted
= 0.01 - 2 x 0.0033
= 0.0034 mol
6) moles of HCl reacting = 2 x moles of H2 produced
= 2 x 0.0033
= 0.0066 mol
7) moles of Zn reacting = mass of Zn taken/molar mass of Zn
with,
mass of Zn taken = 0.2158 g
we get,
moles of Zn reacting = 0.2158 g/65.38 g/mol
= 0.0033 mol
8) ratio of moles of HCl reacting to the moles of Zn reacting = (0.0066/0.0033)
= 2
9) ratio of moles of H2 collected to moles of Zn reacting = (0.0033/0.0033)
= 1
10) Balanced equation of reaction between Zn and HCl
Zn(s) + 2HCl(aq) ---> ZnCl2(aq) + H2(g)
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