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3 years ago

By definition 12 grams of carbon-12 must contain how many atoms?

1 answer:

5 0

It is defined as the amount of a substance that contains as many particles as there are atoms in 12 grams of pure carbon-12. So, 1 molecule contains 6.022×10^23 elementary entities of the substance.

Hope that helps

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6. Look carefully at the following diagram. It does not obey the law of conservation of matter. Explain why it does not follow t

Basile [38]

Answer:

Sort of answer, but it'll lead you in the right direction I hope.

Explanation:

I mean, ofc, the molecules or atoms or whatever the circles are can't be put together that way bc matter says so. It looks like the other diagram is showing water or gas, and if it were turning into the one on the right, then it would usually either settle into water if it was gas or become a single solid object like water. If this is gas, then it doesn't make sense, because gas particles are always separate from each other.

5 0

2 years ago

What mass of Al contains the same number of atoms as 33.5g of Au

wel

Stoich questions...

1) convert the grams of Au to moles
(33.5g)/(196.7g/mol)=___x___

2)find how many atoms are in that many moles by multiplying it by avogadro's number.

x(moles of Au)*(6.02*10^23)=?

3)now that you have found the number of atoms of gold, convert it to grams of aluminum by multiplying it by Avogadro's number and multiplying it by the atomic mass of aluminum.
( ? )(6.02*10^23)(26.98g/mol)= (mass of Al)

5 0

3 years ago

An "empty" container is not really empty if it contains air. How may moles of nitrogen are in an "empty" two-liter cola bottle a

Lisa [10]

Answer:

1. 0.0637 moles of nitrogen.

2. The partial pressure of oxygen is 0.21 atm.

Explanation:

1. If we assume ideal behaviour, we can use the Law of ideal gases to find the moles of nitrogen, considering that air composition is mainly nitrogen (78%), oxygen (21%) and argon (1%):

$V_{N_2}=V_{T}\times 0.78=2L \times 0.78 =1.56 L\\PV=nRT\\n_{N_2}=\frac{PV}{RT}=\frac{1 atm\times 1.56 L}{0.0821\frac{atmL}{molK}\times 298 K}\\n_{N_2}= 0.0637 mol$

2. Now, in order to find he partial pressure of oxygen we need to find the total moles of air, and then the moles of oxygen. Then, we use these results to determine the molar fraction of oxygen, to multiply it with total pressure and get the partial pressure of oxygen as follows:

$n_{total}=\frac{1 atm \times 2L}{0.0821 \frac{atmL}{molK}298K}=0.0817 mol$

$V_{O_2}=2L \times 0.21 = 0.42 L\\n_{O_2}=\frac {1atm \times 0.42 L}{0.0821 \frac{atm L}{mol K}298 K}=0.0172 mol\\X_{O_2}=\frac{n_{O_2}}{n_{total}}=\frac{0.0172 mol}{0.0817 mol}= 0.21$

$P_{O_2}=X_{O_2} \times P = 1 atm \times 0.21 = 0.21 atm$

As you see, the molar fraction and volume fraction are the same because of the assumption of ideal behaviour.

3 0

2 years ago

Sodium metal reacts with water to produce hydrogen gas according to the following equation: 2Na(s) + 2H2O(l)2NaOH(aq) + H2(g) Th

Maru [420]

Answer:

Number of moles of sodium reacted = 0.707 moles

Explanation:

P(H₂) = P(T) – P(H₂O)

P(H₂) = 754 – 17.5 = 736.5 mm Hg

Use the ideal gas equation which

PV= nRT, where P is the pressure V is the volume, n is the number of moles R is the Gas Constant and T is temperature

<u>Re- arrange to calculate the number of moles and using the data provided</u>

n = P x V/R x T

n =736.5 x 8.77/62.36367 x (mmHg/mol K) x (20 + 273)

n = 0.35348668

n = 0.353 moles H₂

<u>from the equation we know that</u>

0.353 mole H₂ x 2mole Na/1mole H₂, So

0.353 x 2 = 0.707 mole Na

The number of moles of Sodium metal reacted were 0.707 moles.

3 0

2 years ago

. Calculate the pH of a solution made by dissolving 1.87 g of sodium caproate, NaC6H11O2, Kb =

scoray [572]

Answer:

Hindi ko po alam pero subukan ko pong sagutan yan

8 0

2 years ago