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3 years ago

A compound contains 16.7 g of iridium and 10.3 g of selenium, what is its empirical formula?

Chemistry

1 answer:

Westkost [7]3 years ago

5 0

Answer:

THE EMPIRICAL FORMULA OF THE COMPOUND IS Ir Se2

Explanation:

Iridium = 16.7 g

Selenium = 10.3 g

Total mass = 16.7 + 10.3 = 27 g

To calculate the empirical formula, we first calculate the percentage com[position of the individual elements.

Percentage composition of iridium = 16.7 / 27 * 100 = 61.85 %

Percentage composition of selenium = 10.3 / 27 * 100 = 38.15 %

Next is to divide the percentage composition of each element by their respective molecular masses

Molecular mass of iridium = 192 g/mol

Molecular mass of selenium = 79g/mol

Iridium = 61.85 / 192 = 0.3221

Selenium = 38.15 / 79 = 0.4829

Next is to divide the values by the smaller of the two values

Iridium = 0.3221 / 0.3221 = 1

Selenium = 0.4829 / 0.3221 = 1.5

Next is to round up the values to a whole number

Iridium = 1

Selenium = 2

The empirical formula therefore is Ir Se2

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Final temperature = 100°C

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Solution:

Specific heat capacity: Cp

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Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = Final temperature = initial temperature

ΔT = 100°C - 20°C

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Given data:

Mass of Al = ?

Initial temperature = 60°C

Final temperature = 30°C

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Q = m.c. ΔT

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m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = Final temperature = initial temperature

ΔT = 30°C - 60°C

ΔT = -30°C

120 j = m × 0.897 j/g.°C × -30°C

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m = 120 j / -26.91 j/g

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Change in temperature = ?

Cp = 0.502 j/g.°C

Heat added= 30.0 j

Solution:

Specific heat capacity: Cp

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

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3 years ago

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lianna [129]

Answer:

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Explanation:

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The conversion of P(torr) to P(atm) is shown below:

$P(torr)=\frac {1}{760}\times P(atm)$

So,

Pressure = 754 / 760 atm = 0.9921 atm

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Volume = 3.1 L

Using ideal gas equation as:

PV=nRT

where,

P is the pressure

V is the volume

n is the number of moles

T is the temperature

R is Gas constant having value = 0.0821 L.atm/K.mol

Applying the equation as:

0.9921 atm × 3.1 L = n × 0.0821 L.atm/K.mol × 294 K

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Surface are = 1257 cm²

For a sphere, Surface area = 4 × π × r² = 1257 cm²

r² = 1257 / 4 × π ≅ 100 cm²

r = 10 cm

The volume of the sphere is :

$V=\frac {4}{3}\times \pi\times r^3$

Where, V is the volume

r is the radius

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V = 4190.4762 cm³

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n = 0.1274 moles

Using ideal gas equation as:

PV=nRT

Applying the equation as:

P × 4.19 L = 0.1274 × 0.0821 L.atm/K.mol × 273 K

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4 0

3 years ago

A solution contains an unknown mass of dissolved barium ions. When sodium sulfate is added to the solution, a white precipitate

AlladinOne [14]

The given question is incomplete. The complete question is as follows.

A solution contains an unknown mass of dissolved barium ions. When sodium sulfate is added to the solution, a white precipitate forms. The precipitate is filtered and dried and then found to have a mass of 212 mg. What mass of barium was in the original solution? (Assume that all of the barium was precipitated out of solution by the reaction.)

Explanation:

When $Ba^{2+}$ and $Na_{2}SO_{4}$ are added then white precipitate forms. And, reaction equation for this is as follows.

$Ba^{2+} + SO^{2-}_{4} \rightarrow BaSO_{4}$

It is given that mass (m) is 212 mg or 0.212 g (as 1 g = 1000 mg). Molecular weight of $BaSO_{4}$ is 233.43.

Now, we will calculate the number of moles as follows.

No. of moles = mass × M.W

= $\frac{0.212}{233.43}$

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Hence, it means that 0.00091 mol of $Ba^{2+}$ . Now, we will calculate the mass as follows.

Mass = moles × MW

= $0.00091 \times 137.327$

= 0.124 grams or 124 mg of barium

Thus, we can conclude that mass of barium into the original solution is 124 mg.

8 0

3 years ago