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3 years ago

Which of the following is evidence of a chemical change?

Chemistry

2 answers:

krek1111 [17]3 years ago

5 0

<span>the formation of a gas
</span>

larisa86 [58]3 years ago

5 0

Answer:

the formation of a gas

Explanation:

The chemical change is one in which some chemical reaction occur.

a) Phase change : it is simply change of one state of matter to another.

For example conversion of ice to liquid water, where there is no change in chemical composition of water and only the physical state is changing.

b) formation of gas: it is possible when some substance breaks into some other components or some substance reacts with other. This is definitely a chemical change as bonds will break and may be new bonds will form.

For example decomposition of calcium carbonate gives carbon dioxide (a gas) and calcium oxide.

c) mass change: it could be due to evaporation of water from a substance. Which must be a physical change.

d) surface area: change in surface is area must be due to change in state or physical modifications in state of a substance.

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7. NH2CO2NH4(s) when heated to 450 K undergoes the following reaction to produce a system which reaches equilibrium: NH2CO2NH4(s

Taya2010 [7]

Answer:

Value of equilibrium constant is 0.0888

Explanation:

Both $NH_{3}$ and $CO_{2}$ are gaseous. Hence equilibrium constant depends upon partial pressures of $NH_{3}$ and $CO_{2}$ .

Initially no $NH_{3}$ and $CO_{2}$ were present.

Hence mole fraction of $NH_{3}$ and $CO_{2}$ at equilibrium can be calculated from coefficient of $NH_{3}$ and $CO_{2}$ in balanced equation.

Mole fraction of $NH_{3}$ = (number of moles of $NH_{3}$ )/(total number of moles of $NH_{3}$ and $CO_{2}$ ) = $\frac{2moles}{(2+1)moles}=\frac{2}{3}$

Mole fraction of $CO_{2}$ = (number of moles of $CO_{2}$ )/(total number of moles of $NH_{3}$ and $CO_{2}$ ) = $\frac{1moles}{(2+1)moles}=\frac{1}{3}$

Let's assume both $CO_{2}$ and $NH_{3}$ behaves ideally.

Therefore partial pressure of $NH_{3}$ , $P_{NH_{3}}= x_{NH_{3}}.P_{total}$ and P_{CO_{2}}= x_{CO_{2}}.P_{total}

Where x represents mole fraction

So, $P_{NH_{3}}=\frac{2}{3}\times 0.843atm=0.562atm$

$P_{CO_{2}}=\frac{1}{3}\times 0.843atm=0.281atm$

So, $K_{p}=P_{NH_{3}}^{2}.P_{CO_{2}}=(0.562)^{2}\times 0.281=0.0888$

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3 years ago

After creating a prototype, which of the following would not be an appropriate next step in the design process of a new technolo

Ivanshal [37]

I would say D but i am not entirely sure

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Early life arose in an oxygen-free environment, but if any of these microbes had somehow come in contact with oxygen, the most l

Leya [2.2K]

Answer:

the effect of oxygen on these types of microbes is it will kill them.

Explanation:

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3 years ago

In which of the following situstions would convection currents occur

andriy [413]

I believe your answer should be C because the heat would move from the soup to the spoon.

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3 years ago

Read 2 more answers

Which of the following is the correct formula to calculate percent by mass? [Mass of solution (g) + mass of solute (g)] × 100 [M

cricket20 [7]

Answer:

Percent by mass is calculated by tihis formula, Mass of solute (g) ÷ mass of solution (g)] × 100.