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Scorpion4ik [409]
3 years ago
7

A 0.500 g sample of He at STP has a volume that is one-half that of an unknown pure gas also at STP. The unknown pure gas sample

has a mass of 36.5 g. What is the molar mass of the unknown gas?
Chemistry
1 answer:
Anuta_ua [19.1K]3 years ago
4 0

Answer:

Molar mass of the unknown gas: 146 g /mol

Explanation:

At STP, any "ideal" gas is contained in a volume of 22.4L. This situation, for 1 mol of gas. In this case we have:

0.5 g / 4 g/mol = 0.125 moles of He

These amount of He occupies 0.125 mol . 22.4L / 1 mol = 2.8 L so the double of volume will be occupied by the unkown gas.

22.4 L / 1 mol = (2.8 L . 2) / x moles

22.4L / 1 mol = 5.6 L / x mol

x mol = 5.6L / 22.4L → 0.25 moles

To determine the molar mass of the unknown gas → 36.5 g / 0.25 mol = 146 g /mol

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Chlorine can be prepared in the laboratory by the reaction of manganese dioxide with hydrochloric acid. HCl(aq), as described by
melisa1 [442]

Answer:

0.88 g

Explanation:

Using ideal gas equation to calculate the moles of chlorine gas produced as:-

PV=nRT

where,

P = pressure of the gas = 805 Torr

V = Volume of the gas = 235 mL = 0.235 L

T = Temperature of the gas = 25^oC=[25+273]K=298K

R = Gas constant = 62.3637\text{torr}mol^{-1}K^{-1}

n = number of moles of chlorine gas = ?

Putting values in above equation, we get:

805torr\times 0.235L=n\times 62.3637\text{ torrHg }mol^{-1}K^{-1}\times 298K\\\\n=\frac{805\times 0.235}{62.3637\times 298}=0.01017\ mol

According to the reaction:-

MnO_2+4HCl\rightarrow MnCl_2+2H_2O+Cl_2

1 mole of chlorine gas is produced when 1 mole of manganese dioxide undergoes reaction.

So,

0.01017 mole of chlorine gas is produced when 0.01017 mole of manganese dioxide undergoes reaction.

Moles of MnO_2 = 0.01017 moles

Molar mass of MnO_2 = 86.93685 g/mol

So,

Mass=Moles\times Molar\ mass

Applying values, we get that:-

Mass=0.01017moles \times 86.93685\ g/mol=0.88\ g

<u>0.88 g of MnO_2(s) should be added to excess HCl (aq) to obtain 235 mL of Cl_2(g) at 25 degrees C and 805 Torr.</u>

6 0
3 years ago
The lac repressor protein binds to the operator when it is _____.
Thepotemich [5.8K]
The lac repressor protein binds to the operator when it is active. The lac repressor is a protein or a DNA-bounding protein as it is called. The lac repressor also involves the lactose metabolism and it is also responsible for the transcription of three lac genes.
8 0
3 years ago
NASA communicates with the Space Shuttle and International Space Station using Ku-band microwave radio. Suppose NASA transmits a
Tanya [424]

Answer:

A = 0.023 m

Explanation:

The relation between the frequency of a radiation and its wavelength is given by the following expression.

where,

c is the speed of light (it has a constant value of 3.00 x 108 m/s)

A is the wavelength of the radiation v is the frequency of the radiation

In this case, the frequency is 13 GHz = 13 x

10° Hz = 13 x 1o° s-

The wavelength associated with this frequency is:

A = c/v = (3.00 x 10° m/s)/(13 x 10° s-") = 0.023

8 0
3 years ago
A mixture containing nitrogen, hydrogen, and iodine established the following equilibrium at 400 °C:2NH3(g) + 3I2(g) ⇌ N2(g) + 6
miss Akunina [59]

Answer: The value of K_{c} for this reaction is 250000.

Explanation:

The given equation is as follows.

2NH_{3}(g) + 3I_{2}(g) \rightleftharpoons N_{2}(g) + 6HI(g)

N_{2}(g) + 3H_{2}(g) \rightleftharpoons 2NH_{3}(g); K_{c_{1}} = 0.50   ... (1)

H_{2}(g) + I_{2}(g) \rightleftharpoons 2HI(g); K_{c_{2}} = 50  ... (2)

To balance the atoms, multiply equation (2) by 3. Hence, the equation (2) can be re-written as follows.

3H_{2}(g) + 3I_{2}(g) \rightleftharpoons 6HI(g); K_{c_{2}} = (50)^{3}  ... (3)

Now, subtract equation (1) from equation (3). So, the equation formed will be as follows.

3I_{2} - N_{2} \rightleftharpoons 6HI - 2NH_{3}

This equation can also be re-written as follows.

3I_{2} + 2NH_{3} \rightleftharpoons N_{2} + 6HI

This equation is similar to the equilibrium equation given to us.

Therefore, during this subtraction the equation constants get divided as follows.

K^{'}_{c} = \frac{K_{c_{2}}}{K_{c_{1}}}\\= \frac{(50)^{3}}{0.50}\\= 250000

Thus, we can conclude that the value of K_{c} for this reaction is 250000.

6 0
3 years ago
What is the chemical formula for marble?
Maru [420]

Calcium carbonate is <span>marble.
CaCo</span>₃ is marble.
7 0
3 years ago
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