What does the number below each element's symbol represent?

Aqueous solutions of Na2CO3 and Ca(NO3)2, 0.10 M each, are combined. A white precipitate is observed in the container after mixi

anzhelika [568]

The question is incomplete. Here is the complete question.

Aqueous solutions of $Na_{2}CO_{3}$ and $Ca(NO_{3})_{2}$ , 0.10 M each, are combined. A white precipitate is observed in the container after mixing. he precipitate is filtered andcarefully rinsed with distilled water to remove other ions. A sample of the precipitate is added to 100 mL of 0.1 M NaCl. A second sample of the precipitate is then added to 100 mL of 0.1 M HCl. What would be observed in each case?

Observation upon Observation upon

addition of precipitate addition of precipitate

to NaCl(aq) to HCl(aq)

(A) additional precipitates forms no visible reaction occurs

(B) no visible reaction occurs gas is produced and some precipitate dissolves

(C) no visible reaction occurs no visible reaction occurs

(D) additional precipitates forms gas is produced and some

precipitate dissolves

Answer: (B) No visible reaction occurs; Gas is produced and some precipitate dissolves

Explanation: When aqueous solutions of $Na_{2}CO_{3}$ and $Ca(NO_{3})_{2}$ are combined, it reacts according to the following balanced equation:

$Na_{2}CO_{3}+Ca(NO_{3})_{2}$ → $CaCO_{3}_{(s)}+2NaNO_{3}_{(aq)}$

forming calcium carbonate ( $CaCO_{3}$ ), which, as it is insoluble in water, precipitates as a solid of the color white. This process is Precipitation and this reaction is a Precipitation Reaction.

When calcium carbonate reacts with NaCl it produces:

$CaCO_{3}+2NaCl$ → $CaCl_{2}+Na_{2}CO_{3}$

Now, calcium chloride is an inorganic compound very soluble in water, so, in this reaction, there are no precipitate and no visible reaction occurs.

When $CaCO_{3}$ reacts with hydrochloridric acid, the balanced reaction is

$CaCO_{3}+2HCl$ → $CaCl_{2}+H_{2}CO_{3}$

which, also produces calcium chloride and carbonic acid.

Both are soluble in water but, when carbonic acid is in an "aqueous state", carbonic acid, it dissociates, forming carbon dioxide and water. Therefore, gas is produced and some precipitate dissolves.

In conclusion, sentence B is the correct alternative.

5 0

3 years ago

Which higher heat transfer ?

stellarik [79]

Answer:

b)boiling water

Explanation:

High heat is transferred with the thermal conduction process, also called diffusion. Always occurs from a region of higher temperatures to a region of lower temperatures. The flow of fluid may be forced into external processes.

As the particles rapidly move and vibrate and the transfer of heat from one state to the other by the interaction of particles and rate of heat lost has to be the same as absorbed heat during vaporization at the same fluid pressure.

A component of heat transfer can be seen as a heat sink in which transfers the heat generated within any medium. Thus evaporative cooling happens after the vapor is added to the surrounding air.

3 0

3 years ago

ASAP plz I will give the brainliest

BigorU [14]

The answer for the first question is A. Single covalent bond.

The answer for the second question is C. Carbon dioxide.

3 0

3 years ago

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Question: When the ore lead (ii) sulfide burns in oxygen, the products are solid lead (ii) oxide and sulfur dioxide gas.

Anuta_ua [19.1K]

I believe what you are trying to ask here is the balanced chemical reaction. We first identify the chemical formula of the substances.

Lead(II) sulfide = PbS
Oxygen = O2
Lead(II) oxide = PbO
Sulfur dioxide = SO2

The balanced chemical reaction is written as:

PbS + 3/2O2 = PbO + SO2

4 0

3 years ago

What causes winter in the Northern Hemisphere? Choose all that apply.

Mandarinka [93]

Option D : The northern hemisphere is tilted away from the sun.

8 0

2 years ago

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