Chemistry, 10.03.2021 17:50 stephanieeping

Calcium carbonate, CaCO3(s), the principal compound in limestone, decomposes upon heating to CaO(s) and CO2(g). A sample of CaCO3 is decomposed, and the carbon dioxide is collected in a 250 mL flask. After decomposition is complete, thegas has a pressure of 1.3 atm at a temperature of 31 °C. How many moles of CO2 gas were generated?

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Answer from: mvtthewisdead

n = 0.01302 moles

Explanation:

Pressure = 1.3 atm

Temperature = 31 °C + 273 = 304 K ( Converting to kelvin temperature)

Number of moles = ?

Volume = 250 mL = 0.250 L

These quantities are related by the equation below;

PV = nRT

n = PV / RT

n = (1.3 * 0.250) / (0.0821 * 304)

n = 0.01302 moles

Answer from: Quest

Answer: abeexplanation:

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

Answer from: Quest

cytokinesis is the splitting of a cell membrane to form 2 identical daughter cells. it's similar to mitosis as both cells have identical copies of dna and cytokinesis is a step in the mitotic cycle.

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Calcium carbonate, CaCO3(s), the principal compound in limestone, decomposes upon heating to CaO(s)...

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