A student adds 12.00 g of dry ice (solid CO_2) to an empty balloon. What will be

Question

A student adds 12.00 g of dry ice (solid CO_2) to an empty balloon. What will be the volume of the balloon at STP after all the dry ice sublimes to gaseous CO_2? 1.62 L 2.01 06.11 L 9.03 L None of these An unknown diatomic gas has a density of 1.25 g/L at STP What is the identity of the gas? O_2 N_2 Cl_2 Br_2 None of these Use Table A provided in this exam to answer this question. A 5.00 g sample of one of the substances listed in Table A was heated from 34.3 degree C to 64.2 degree C, requiring 133 J to do so. Which substance was it? H_2 O(l) Al(s) Fe(s) Hg(l) C(s) Predict which pair of substances would form molecular solids CO_2 and NaCl CH_4 and CO_2 CH_3 CH_3 and CaCO_3 CH_3 OH and KBr None of these The graph on the right shows the vapor pressures of four substances at various temperatures are. If the atmospheric pressure was 80 KPa, which substances could boil at 60 degree C? Ethanol Ethanol, Water, and Ethanoic Acid Chloroform Chloroform, Ethanol None of the substance

Explanation / Answer

1. Using the ideal gas law:
PV = nRT ---> V = nRT/P
n = 12/44 = 0.2727 moles

V = 0.2727 * 0.0821 * 273 / 1 = 6.11 L

2. We have the density so:
n = m/MW and density (d) = m/V so replacing these in the ideal gas law:

P = mRT / V MW
P = dRT/MW --> From here, we solve for MW:
MW = dRT/P

MW = 1.25 * 0.0821 * 273 / 1
MW = 28.01 g/mol. This corresponds to N2.

For now, I'll answer these. The others post them in another question if you wish.

Hope this helps

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