Question

How many molecules of co2 are in a 500. 0 ml container at 780 mm hg and 135°c? 8. 76 × 1021 molecules 9. 23 × 1021 molecules 5. 50 × 1021 molecules 2. 65 × 1022 molecules 2. 79 × 1022 molecules.

Answer 1

Step 1:

ok we have to use the formula PV=nRT

p=Pressure (must be converted to atm)= 780 mmHg

1 amt= 760 mmHg use this as a conversion factor

780 mmHg (1 atm/760 mmHg)= 1.026

V= Volume= 5.00 mL = o.5 L

n=number of moles which we have to find first

R= 0.0821

T(convert to Kelvins by adding 273.15 to the celsius temperature)= 135 C + 273.15= 408.15 k

Now plug in->

(1.026 atm)(o.5 L)= n(0.0821)(408.15 K)

(1.026 atm)(0.5 L)= n(33.509115)

(0.513)= n(33.509115)

n(number of moles)= 0.01532 mol

Now we have to convert to moles using Avagodro's number which states that 1 mol = 6.022 x 10^23 molecules or atoms

So 0.01532 mol (6.022 x 10^23 number of molesules)/ (1 mol) = 9.225704 x 10^21 = 9.226 x 10^21 colecules

Step 2

You must transfer pressure into pascals, 780 mm Hg = 103991 Pa

135*C = 408.15 k

then from the equation pV = nRt

n = pV / RT (T in Kelvins, V in M^3)

n = 103991 x 500 x 10^-6 / (8.314 x 408.15)= 0.015322 moles of N2

1 mol of everything is 6.022 x 10^23 particles, so 0.15322 moles is 0.15322 x 6.022 x 10^23 = 9.2269084 x 10^21 molecules

Explanation:

Hope this helps :)