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Alex
3 years ago
8

2. STEM The mass of an atom of helium is about 4.002 atomic units.

Chemistry
1 answer:
Anit [1.1K]3 years ago
6 0

Answer:

The approximate mass of beryllium is 9.0045 u.

Explanation:

Given data:

mass of helium= 4.002 u

mass of beryllium which is 2.25 times of mass of helium= ?

Solution:

we will multiply the mass of helium with 2.25 times,

4.002 u × 2.25 = 9.0045 u

so the mass of beryllium atom would be 9.0045 u.

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CH4 with pressure 1 atm and volume 10 liter at 27°C is passed into a reactor with 20% excess oxygen, how many moles of oxygen is
BaLLatris [955]

Answer : The moles of O_2 left in the products are 0.16 moles.

Explanation :

First we have to calculate the moles of CH_4.

Using ideal gas equation:

PV=nRT

where,

P = pressure of gas = 1 atm

V = volume of gas = 10 L

T = temperature of gas = 27^oC=273+27=300K

n = number of moles of gas = ?

R = gas constant = 0.0821 L.atm/mol.K

Now put all the given values in the ideal gas equation, we get:

(1atm)\times (10L)=n\times (0.0821L.atm/mol.K)\times (300K)

n=0.406mole

Now we have to calculate the moles of O_2.

The balanced chemical reaction will be:

CH_4+2O_2\rightarrow CO_2+2H_2O

From the balanced reaction we conclude that,

As, 1 mole of CH_4 react with 2 moles of O_2

So, 0.406 mole of CH_4 react with 2\times 0.406=0.812 moles of O_2

Now we have to calculate the excess moles of O_2.

O_2 is 20 % excess. That means,

Excess moles of O_2 = \frac{(100 + 20)}{100} × Required moles of O_2

Excess moles of O_2 = 1.2 × Required moles of O_2

Excess moles of O_2 = 1.2 × 0.812 = 0.97 mole

Now we have to calculate the moles of O_2 left in the products.

Moles of O_2 left in the products = Excess moles of O_2 - Required moles of O_2

Moles of O_2 left in the products = 0.97 - 0.812 = 0.16 mole

Therefore, the moles of O_2 left in the products are 0.16 moles.

7 0
3 years ago
A gas occupies a volume of 1.00 L at 25.0°C. What volume will the gas occupy at 1.00 x10^2 °C?
Leno4ka [110]

Answer : The volume of gas occupy at 1.00\times 10^2^oC is, 1.25 L

Explanation :

Charles' Law : It states that volume of the gas is directly proportional to the temperature of the gas at constant pressure and number of moles.

Mathematically,

\frac{V_1}{T_1}=\frac{V_2}{T_2}

where,

V_1\text{ and }T_1 are the initial volume and temperature of the gas.

V_2\text{ and }T_2 are the final volume and temperature of the gas.

We are given:

V_1=1.00L\\T_1=25.0^oC=(25.0+273)K=298K\\V_2=?\\T_2=1.00\times 10^2^oC=((1.00\times 10^2)+273)K=373K

Putting values in above equation, we get:

\frac{1.00L}{298K}=\frac{V_2}{373K}\\\\V_2=1.25L

Therefore, the volume of gas occupy at 1.00\times 10^2^oC is, 1.25 L

3 0
3 years ago
If the pressure of a gas sample is quadrupled and the absolute temperature is doubled, by what factor does the volume of the sam
Natasha_Volkova [10]

Answer:

D) 1/2

Explanation:

Using Ideal gas equation for same mole of gas as

\frac {{P_1}\times {V_1}}{T_1}=\frac {{P_2}\times {V_2}}{T_2}

Given,

P₂ = 4P₁

T₂ = 2T₁

Using above equation as:

\frac {{P_1}\times {V_1}}{T_1}=\frac {{P_2}\times {V_2}}{T_2}

\frac {{P_1}\times {V_1}}{T_1}=\frac {{4\times P_1}\times {V_2}}{2\times T_1}

V_2=\frac{1}{2}\times V_1

<u>The volume change by half of the original.</u>

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3 years ago
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The highest tides of the year are neap tides. True False
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I think its false...
8 0
3 years ago
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33 protons 36 electrons 45 neutrons
Artist 52 [7]

As has an atomic number of 33, so it has 33 protons.  

It has a charge of 3-, so there are three more electrons than protons. Thus, there are 36 electrons.  

It has a mass of 75, which is the sum of neutrons and protons.  

33+n=75 ---> n = 75 - 33 = 42 neutrons  

The answer is e) 33 protons, 42 neutrons and 36 electrons.

6 0
3 years ago
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