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3 years ago

What volume, in mL, of a 0.539 M solution of NaBH4 is required to produce 0.579 g of B2H6? H2SO4 is present in excess.

Chemistry

1 answer:

Fittoniya [83]3 years ago

5 0

Answer:

70.872 mL

Explanation:

The reaction of Sodium borohydrate with sulfuric acid to form diborane is shown below as:

2 NaBH₄ + 2 H₂SO₄ = B₂H₆ + 3 H₂ + 2 NaSO₄

Given mass of B₂H₆ = 0.579 g

Molar mass of B₂H₆ = 27.66 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus, moles of B₂H₆are:

$moles= \frac{0.579\ g}{27.66\ g/mol}$

$moles= 0.0191\ mol$

From the reaction,

1 mole of B₂H₆ is produced when 2 moles of NaBH₄ react with acid.

So,

0.0191 moles of B₂H₆ is produced when 2×0.0191 moles of NaBH₄ react with acid.

Moles of NaBH₄ required = 0.0382 moles

Given, Molarity of NaBH₄ = 0.539 M

Molarity = Moles / Volume

Volume = Moles / Molarity = 0.0382 moles / 0.539 M = 0.070872 L

Also, 1L = 1000 mL

So,

Volume = 70.872 mL

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xenn [34]

Answer:

4. False

5. False.

6. (b) One mole of a substance contains 6.022 x 10²³ particles of that substance

(c) There are 6.022 x 10²³ carbon atoms in 12.00 g of carbon-12.

7. The correct option is (A) 3H₂SO₄

8. (b) 1.71 * 10³⁷ atoms of hydrogen

Explanation:

4. 1.00 mole of Ca(NO3)2 contains the same mass of N as 1.00 mole of NaNO3 is False because 1 mole of Ca(NO3)2 contains 2 moles (28 g) of N atoms whereas 1 mole of NaNO3 contains 1 mole (14 g) of N atoms

5. The theoretical yield of a reaction is generally less than the actual yield is False because it is the actual yield of a reaction that is always less than the theoretical yield due to some incomplete reactions.

The actual yield is obtained from carrying out the actual reaction while the theoretical yield is calculated from the equation of the reaction.

6. A mole of a substance is defined as the amount of that substance which contains as many elementary particles as there are in 12 g of carbon-12.

From experiments, it was discovered that 12 g of carbon -12 contains 6.02 * 10²³ atoms, therefore, a mole of a substance can also be defined as the amount of that substance which contains 6.02 * 10²³ particles of that substance.

(a) One mole of a substance contains as many particles as exactly 12 amu of carbon-12 is false because 12 amu is the mass of 1 atom of carbon-12 and not a mole of carbon-12.

(b) One mole of a substance contains 6.022 x 1023 particles of that substance is true from the definitions above

(d) Because it is heavier, a mole of iodine atoms contains more particles than a mole of bromine atoms is false because, irrespective of difference in their masses, a mole of all substances contain the same number of particles- 6.02 * 10²³.

7. The balanced chemical equation of the reaction of sulfuric acid with hematite (Fe2O3) to produce iron (III) sulfate and water is as follows: .

Fe₂O₃ + 3H₂SO₄ -----> Fe₂(SO₄)₃ + 3H2O

The correct option is (A) 3H₂SO₄

8. Mass of natural gas = 1.14 * 10¹¹ Kg.

Mass of natural gas in grams = 1.14 * 10¹¹ * 10³ g = 1.14 * 10¹⁴ g

Molar mass of CH₄ = 16g/mol

Number of moles of CH₄ in 1.14 * 10¹⁴ g = 1.14 * 10¹⁴ g/ 16 gmol⁻¹ = 7.125 * 10¹² moles

1 mole of CH₄ contains 4 moles of hydrogen atoms.

7.125 * 10¹² moles of CH₄ will contain 4 * 7.125 * 10¹² moles of hydrogen atoms = 2.85 * 10¹³ moles of hydrogen atoms

1 mole of hydrogen atoms contain 6.02 * 10²³ atoms of hydrogen

2.85 * 10¹³ moles of hydrogen atoms will contain 2.85 * 10¹³ * 6.02 * 10²³ atoms of hydrogen = 1.71 * 10³⁷ atoms of hydrogen

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3 years ago

Workout the number of atoms in 0.5 moles of iron?

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Answer:

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2 years ago

Heat applied to reactants causes a faster chemical reaction. Heat is considered _____.

Lina20 [59]

Heat applied to reactant causes a faster chemical reaction. Heat is considered as ACTIVATION ENERGY.

Activation energy is the minimum amount of energy which reactants must possess in order to undergo a chemical reaction. When heat is applied to a particular set of reactants, the heat increases the kinetic energy of the reacting particles, thus enabling them to move around more rapidly. This increases the rate of collision among the reacting particles and empower the reacting particles to overcome the energy barriers and to form the products.

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3 years ago

A sample of helium occupies a volume of 180.0 ml at a pressure of 0.800 atm and a temperature of 29°C. What will be the

Brrunno [24]

Answer:

If the volume of the container is decreased to 90.0 ml and the pressure is increased to 1.60 atm the temperature will be 302 °K

Explanation:

Boyle's law says that "The volume occupied by a given gas mass at constant temperature is inversely proportional to the pressure", which is expressed mathematically as:

P * V = k

Charles's Law consists of the relationship between the volume and temperature of a certain amount of ideal gas, which is maintained at a constant pressure, by means of a proportionality constant that is applied directly. In summary, Charles's law is a law that says that when the amount of gas and pressure are kept constant, the ratio between volume and temperature will always have the same value:

$\frac{V}{T} =k$

Finally, Gay Lussac's law establishes that as the temperature increases, the gas molecules move more quickly and therefore the number of collisions against the walls increases, that is, the pressure increases since the container is of fixed walls and its volume can not change. Therefore, the ratio of pressure to temperature always has the same value (it is constant).

$\frac{P}{T}=k$

Combined law equation is the combination of three gas laws called Boyle's, Charlie's and Gay-Lusac's law:

$\frac{P*V}{T}=k$

Having a state 1 at the beginning and a state 2 at the end is fulfilled:

$\frac{P1*V1}{T1}=\frac{P2*V2}{T2}$

In this case, you know:

P1= 0.800 atm
V1= 180 mL= 0.180 L (being 1 L=1000 mL)
T1= 29 °C= 302 °K
P2= 1.60 atm
V2= 90 mL= 0.09 L
T2=?

Replacing:

$\frac{0.800 atm*0.180L}{302 K}=\frac{1.60 atm*0.09L}{T2}$

Solving:

$T2*\frac{0.800 atm*0.180L}{302 K}=1.60 atm*0.09L$

$T2=\frac{1.60 atm*0.09L}{\frac{0.800 atm*0.180L}{302 K}}$

T2= 302 °K

If the volume of the container is decreased to 90.0 ml and the pressure is increased to 1.60 atm the temperature will be 302 °K

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3 years ago

Describe the difference beetween an extensive and intesive property

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Extensive properties, such as mass and volume, depend on the amount of matter being measured. Intensive properties, such as density and color, do not depend on the amount of the substance present. Physical properties can be measured without changing a substance's chemical identity.

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3 years ago