How much calcium oxide would be made by the thermal decomposition of 25 grams of calcium carbonate? CaCO3 -> CaO + CO2


A. 28 grams

B. 12 grams

C. 14 grams

D. 25 grams

14 grams of calcium oxide would be produced by thermal decomposition of 25 grams of calcium carbonate.

Explanation:

You know:

CaCO₃ → CaO + CO₂

In the first place, by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) the following quantities react and are produced:

Being:

the molar mass of the compounds participating in the reaction is:

Then, by stoichiometry of the reaction, the following mass amounts of the compounds participating in the reaction react and are produced:

You can then apply the following rule of three: if by stoichiometry of the reaction 100 grams of calcium carbonate CaCO₃ produce 56 grams of calcium oxide CaO, 25 grams of CaCO₃ how much mass of CaO will it produce?

mass of calcium oxide= 14 grams

14 grams of calcium oxide would be produced by thermal decomposition of 25 grams of calcium carbonate.

state the principle of separating two immiscible liquids by separating funnel. describe an activity with diagram to separate a mixture of water and kerosene oil. answer: immiscible layers separate out in layers depending on their densities in separating funne

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.