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3 years ago

Gas y effuses half as fast as o2. what is the molar mass of gas y?

1 answer:

4 0

To solve this question, we will use Graham's law which states that:
(R1 / R2) ^ 2 = M2 / M1 where
R1 and R2 are the rates of effusion and M1 and M2 are the molar masses of the two gases.
From the periodic table, we can calculate the molar mass of O2 as follows:
molar mass of O2 = 2*16 = 32 grams

Therefore we have:
R1 / R2 = Ry / RO2 = 1/2
M1 is My we want to get
M2 is molar mass of O2 = 32 grams
Substitute in the above equation to get the molar mass of y as follows:
(1/2) ^2 = (32/My)
1/4 = 32/My
My = 32*4 = 128

Therefore, molar mass of gas y = 128 grams

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Starting with 250 mL of a 0.250 M solution of HBr; a) Calculate the initial pH of the solution.b) Calculate the pH after adding

maxonik [38]

Answer:

pH = 0.602

pH = 1.5

pH = 7

pH = 12.1

Explanation:

a ) To calculate the pH, use the following equation:

pH = -log [H+]

Hbr is a strong acid, so the [H+] concentration can be calculated as follow:

[HBr] = 0.250 M

As acid Hbr:

Hbr = H+ + Br-

As strong acid HBr dissociates at all, so

[HBr] = [H+] = 0.250 M

So the pH:

pH = -log [0.250 M] = 0.602

b) Calculate the pH after adding 250 mL of 0.125M NaOH

In this point, the reactions starts:

HBr + NaOH = H2O + NaBr

- First, we gonna find the mol of each reactant:

HBr:

mol = [M] × L

mol = 0.250 M × 0.250 L

mol = 0.0625 mol HBr

NaOH:

mol = [M] × L

mol = 0.125 M × 0.250L

mol = 0.03125 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.0625 mol HBr – 0.03125 mol HBr = 0.03125 mol HBr

These are the moles free in the solution, and we going to use them to calculate the pH:

pH = -log [ H]

pH = - log [ 0.03125 ] = 1.5

c) Calculate the pH after adding 500 mL of 0.125M NaOH

NaOH:

mol = [M] × L

mol = 0.125 M × 0.500L

mol = 0.0625 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.0625 mol HBr – 0.0625 mol HBr = 0 HBr

pH = 7

d) Calculate the pH after adding 600 mL of 0.125M NaOH.

NaOH:

mol = [M] × L

mol = 0.125 M × 0.600L

mol = 0.075 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.075 mol NaOH – 0.0625 mol NaOH = 00125 NaOH

These are the moles free in the solution, and we going to use them to calculate the pH:

pOH = -log [ OH]

pOH = - log [ 0.0125 ] = 1.90

pH + pOH = 14

pH = 14- pOH = 14 – 1.90 = 12.1

4 0

3 years ago

What would be the mass of 3 moles of water molecules?

ankoles [38]

Answer:

$\boxed {\boxed {\sf A. \ 54 \ grams }}$

Explanation:

To convert from moles to grams, we must use the molar mass.

Recall that water's molecular formula is H₂O. It contains hydrogen and oxygen. Look up the two elements masses on the Periodic Table.

Hydrogen (H): 1.008 g/mol
Oxygen (O): 15.999 g/mol

Now, use these masses to find water's mass. The subscript of 2 tells us there are 2 atoms of hydrogen, so we multiply hydrogen's mass by 2 and add oxygen's.

H₂O= 2(1.008 g/mol) + 15.999 g/mol = 18.015 g/mol

Use the molar mass as a ratio.

$\frac{18.015 \ g \ H_2 O}{ 1 \ mol \ H_2 O}$

Multiply by the given number of moles.

$3 \ mol \ H_2O*\frac{18.015 \ g \ H_2 O}{ 1 \ mol \ H_2 O}$

The moles of water will cancel.

$3 *\frac{18.015 \ g \ H_2 O}{ 1 }$

$3 *{18.015 \ g \ H_2 O}$

$54.045 \ g \ H_2O$

Round to the nearest whole number. The 0 in the tenth place tells us to leave the number as is.

$54 \ g \ H_2O$

There are about 54 grams of water in 3 moles.

7 0

3 years ago

Read 2 more answers

A balance was tested against a standard calibration mass with a certified value of 200.002 g and produced the following readings

wlad13 [49]

Answer:

Precise but not accurate.

Explanation:

We can tell the performance of the balance is precise, because the repeated measurements give values close to one another.

However, the performance of the balance is not accurate, as the mean value of the repeated measurements (195.587) is not close to the value considered as true (in this case the standard calibration mass with a certified value of 200.002 g).

7 0

3 years ago

What is bond stability??

Nookie1986 [14]

Answer:

Bond order is a counting method that gives an idea about numbers of electrons shared between atoms. A species with a higher bond order is more stable. A bond order equal to 2 is a double bond, and a bond order of 3 is a triple bond.

Explanation:

8 0

3 years ago

Read 2 more answers

If a helium balloon is put into a hot oven. What happens to the volume of the balloon?

AveGali [126]

Answer:

What about hot air balloons? They work by similar principles. If you heat up a gas it expands. In the case of a hot air balloon, when the gas inside the balloon expands the extra gas is pushed out the bottom of the balloon, meaning that there are fewer atoms inside the balloon, meaning that the air in the balloon is lighter than the air outside the balloon.

The amount of lifting power is controlled by how hot the air is. If you heat the air inside the balloon 100 degrees F hotter than the outside air temperature, then the air inside the balloon will be about 25 percent lighter than the air outside the balloon. So a cubic foot of air weighs about 35 grams at 32 degrees F. A cubic foot of hot air at 132 degrees F will weigh 25 percent less, or about 26.5 grams. The difference is 8.5 grams or so. So a hot air balloon has to be much bigger to support the same weight, but it will float because hotter air is lighter than cooler air.

Explanation:

The amount of lifting power

6 0

3 years ago