Some kinda gas/reaction question?

Question

50 mL of 2M NaBr is reacted with excess Cl2. The Br2 gas given off is collected. What volume would the gas occupy at 298 K and 1 atm?

Answering this correctly with work shown will get you ten points.

It's only one question... So what???

Please, don't waste my time with stupid answers... I hate people who do that.

Answer 1

2*NaBr + Cl2 ---> 2*NaCl + Br2

in 1000 mL NaBr solution we have 2 moles of NaBr
That would mean that in 50 mL solution we have 50*2/1000 moles NaBr, that would be 0.1 moles NaBr.
2 moles of NaBr give 1 mol of Br2, which means 0.1 moles NaBr would give 0.05 moles of Br2.
298 K and 1 atm are the standard conditions, at which 1 mole of any gas would occupy 22.4 liters. That would mean that our 0.05 moles of Br2 would occupy 0.05*22.4 = 1.12 liters of Br2.

This is the theoretical result. Practically what happens is that Br2 is NOT a gas, it's a liquid. Given that the solution would heat, Br2 vapors will occur, but not all Br2 would be vaporized, so with the data given in the problem we cannot actually calculate the volume of the gaseous Br2 obtained. However, in the purpose of practicing simple chemistry exercises, this problem would serve.

Answer 2

First we must balance the equation so we have an idea of the molar ratios we are dealing with.

x NaBr + y Cl2 ----------> w NaCl + z Br2 (gas)

(This is an oxidation reaction, Chlorine because it is more electronegative than Bromine, will rob the Bromide anion of its electrons to form Chloride anions, leaving Bromine atoms to combine with themselves to form Bromine molecules)

We want whole number coefficients, if set x = 2 and Z = 1 we are balanced for the Bromine.

2 NaBr + y CL2 ----------> w NaCl + Br2

It follows that y = 1 and w = 2

2 NaBr + Cl2 ----------> 2 NaCl + Br2

So for every 2 moles of NaBr (Sodium Bromide) consumed there is one mole of Br2 gas formed.

50ml * 2 Moles of Bromide ions/1000ml = 0.1 mole of Br atoms

Therefore 0.1 mole of Bromide ions makes 0.1 mole of Br atoms that form 0.05 mole of Br2 molecules.

What volume does 0.05 mole of Br2 molecules take up at 298K and 1 atm. That should not be a problem if you apply the ideal gas equation, pv=nrt.

Answer 3

2NaBr + Cl2 ---> 2 NaCl + Br2

50 ml of NaBr divided by 1000 to get to liters, times 2 because the molarity convert moles NaBr to moles Br2 by dividing by 2. you get .05 mol Br2. then plug that into the PV=nRT equation to get 1.22 L Br2

Answer 4

You gotta use the gas equation

PV = nRT

(or PV = NkT)

You are given T and P

You can work out from your chem the n

R is a constant

Find V you doofus

Answer 5

WOW
a whole ten points for doing your homework?

Answer 6

Do your own homework.