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kompoz [17]
3 years ago
15

PLEASE HELP!!!! IT'S DUE TODAY!!!

Chemistry
2 answers:
Dafna1 [17]3 years ago
7 0
I’m pretty sure the answer is B
Hope this helps
LuckyWell [14K]3 years ago
5 0

Answer:

I think it might be C

Explanation:

Im not sure though

Please tell me if im wrong

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Solid sodium hydrogen carbonate, NaHCO3, decomposes on heating according to the equation:
tekilochka [14]

Answer:

See explanation

Explanation:

First, let's write the balanced equation again:

2 NaHCO3(s) <-> Na2CO3(s) + H2O(g) + CO2(g)

Now, we know that the total pressure was 7.76 atm. This total pressure, is the sum of the pressure of water and CO2 like this:

Ptotal = Pwat + PCO2 (1)

This is the dalton's law for partial pressures.

The pressure can be also be relationed with the moles

Ratio of mole = Ratio of pressure

so, taking this in consideration we can say the following:

Pwater/PCO2 = moles water / moles CO2

As the only components exerting pressure are CO2 and Water (Because they are in gas phase), the total pressure can be splitted between the two of them so:

Pwater = Ptotal/2

Pwater = 7.76 / 2 = 3.88 atm

With this pressure, and using the ideal gas equation, we can know the moles of water:

PV = nRT

n = PV/RT     using R = 0.082 L atm / K mol

n = 3.88 * 5 / 0.082 * (160+273)

n = 0.546 moles of water

b) now that we have the moles of water, we can actually know the moles that reacted originally from the sodium carbonate by stechiometry.

2NaHCO3(s) <-> Na2CO3(s) + H2O(g) + CO2(g)    MMCO2 = 84 g/mol

the moles of NaHCO3 initially:

n = 100 / 84

n = 1.19 moles

so, If 1.19 moles of NaHCO3 reacted, and only produces 0.546 moles of water and CO2, then, the remaining moles of NaHCO3 is:

remaining moles = 1.19 - 0.546 = 0.644 moles

therefore the mass remaining:

mCO2 = 0.644 * 84

mCO2 = 54.096 g

c) As it was stated before, only the gaseous components are involved in the pressure, thus, in the kp expression which is:

Kp = Pwater * PCO2

Kp = 3.88 * 3.88

Kp = 15.0544

d) As the total pressure is 7.76 atm and the fact that NaHCO3 is solid, this component is not exerting any pressure in the reaction, as seen in the Kp expression, so it won't matter that if we raise a little the quantity of the reactant, it still has some remaining.

3 0
3 years ago
Tyrosine absorbs maximally at 290 nm. A 0.2162 g sample containing some amount of Tyrosine was placed into a 250.0 mL volumetric
mojhsa [17]

Answer:

B. 0.069 %

Explanation:

It should be initially noted in this answer in particular that, the amino acids tryptophan and tyrosine have a very precise 280 nm absorption rate, which allows a direct A280 size of protein concentration. The 280 nm UV absorbance rate is regularly utilized to approximate protein concentration in laboratories due to its simplistic nature, its affordability and also the ease of usage.

kindly check the attached image below for the solution to the above question.

7 0
3 years ago
⚠️⚠️Plz Help⚠️⚠️
Dmitrij [34]

Answer:

B

Explanation:

just took the test

6 0
2 years ago
An aqueous solution at 25°C has a OH− concentration of 1.9x10−8M . Calculate the H3O+ concentration. Be sure your answer has the
Papessa [141]

Answer:

= 5.26 × 10^-7 M

Explanation:

We know that;

[H3O+][OH-] = 1 x 10^-14

Therefore;

Given; OH− concentration = 1.9x10^−8 M

Then; [H3O+] = (1 x 10^-14)/[OH-]

                      = (1 x 10^-14)/(1.9x10^−8)

                      = 5.26 × 10^-7 M

4 0
3 years ago
Read 2 more answers
an alloy contains 66 g of pure zinc. what is the percentage of zinc in the alloy? express your answer to two significant figures
alekssr [168]

Answer:

ba

Explanation:

6 0
3 years ago
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