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2 years ago

What is the mass of 2.56 × 10–4 moles of Fe2O3? : 6.23 × 105 159.6 g 1.60 × 0–6 g 4.09 × 10–2 g

Chemistry

1 answer:

Monica [59]2 years ago

7 0

Answer:

4.09 × 10⁻² g

Solution:

As we know that,

1 mol of Fe₂O₃ is equal to = 159.69 g

So,

2.56 × 10⁻⁴ mol will be equal to = X g

Solving for X,

X = (159.69 g × 2.56 × 10⁻⁴ mol) ÷ 1 mol

X = 0.04088 g

Or,

X = 0.049 g

Or,

X = 4.09 × 10⁻² g

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The freezing point of ethanol, CH3CH2OH, is -117.300 °C at 1 atmosphere. Kf(ethanol) = 1.99 °C/m

MAXImum [283]

Answer : The molecular weight of this compound is 891.10 g/mol

Explanation : Given,

Mass of compound = 12.70 g

Mass of ethanol = 216.5 g

Formula used :

$\Delta T_f=i\times K_f\times m\\\\T_f^o-T_f=i\times T_f\times\frac{\text{Mass of compound}\times 1000}{\text{Molar mass of compound}\times \text{Mass of ethanol}}$

where,

$\Delta T_f$ = change in freezing point

$T_f^o$ = temperature of pure ethanol = $-117.300^oC$

$T_f$ = temperature of solution = $-117.431^oC$

$K_f$ = freezing point constant of ethanol = $1.99^oC/m$

i = van't hoff factor = 1 (for non-electrolyte)

m = molality

Now put all the given values in this formula, we get

$(-117.300)-(-117.431)=1\times 1.99^oC/m\times \frac{12.70g\times 1000}{\text{Molar mass of compound}\times 216.5g}$

$\text{Molar mass of compound}=891.10g/mol$

Therefore, the molecular weight of this compound is 891.10 g/mol

7 0

2 years ago

A 1.00 g sample of a metal X (that is known to form X ions in solution) was added to 127.9 mL of 0.5000 M sulfuric acid. After a

Semenov [28]

Answer: The metal having molar mass equal to 26.95 g/mol is Aluminium

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$ .....(1)

Molarity of NaOH solution = 0.5000 M

Volume of solution = 0.03340 L

Putting values in equation 1, we get:

$0.5000M=\frac{\text{Moles of NaOH}}{0.03340L}\\\\\text{Moles of NaOH}=(0.5000mol/L\times 0.03340L)=0.01670mol$

The chemical equation for the reaction of NaOH and sulfuric acid follows:

$2NaOH+H_2SO_4\rightarrow Na_2SO_4+H_2O$

By Stoichiometry of the reaction:

2 moles of NaOH reacts with 1 mole of sulfuric acid

So, 0.01670 moles of NaOH will react with = $\frac{1}{2}\times 0.01670=0.00835mol$ of sulfuric acid

Excess moles of sulfuric acid = 0.00835 moles

Calculating the moles of sulfuric acid by using equation 1, we get:

Molarity of sulfuric acid solution = 0.5000 M

Volume of solution = 127.9 mL = 0.1279 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$0.5000M=\frac{\text{Moles of }H_2SO_4}{0.1279L}\\\\\text{Moles of }H_2SO_4=(0.5000mol/L\times 0.1279L)=0.06395mol$

Number of moles of sulfuric acid reacted = 0.06395 - 0.00835 = 0.0556 moles

The chemical equation for the reaction of metal (forming $M^{3+}$ ion) and sulfuric acid follows:

$2X+3H_2SO_4\rightarrow X_2(SO_4)_3+3H_2$

By Stoichiometry of the reaction:

3 moles of sulfuric acid reacts with 2 moles of metal

So, 0.0556 moles of sulfuric acid will react with = $\frac{2}{3}\times 0.0556=0.0371mol$ of metal

To calculate the molar mass of metal for given number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Mass of metal = 1.00 g

Moles of metal = 0.0371 moles

Putting values in above equation, we get:

$0.0371mol=\frac{1.00g}{\text{Molar mass of metal}}\\\\\text{Molar mass of metal}=\frac{1.00g}{0.0371mol}=26.95g/mol$

Hence, the metal having molar mass equal to 26.95 g/mol is Aluminium

6 0

2 years ago

Which substance used during photosynthesis does a plant take in from the soil?

Simora [160]

Answer:

the answer is water

Explanation:

During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose.

3 0

1 year ago

Read 2 more answers

Give the IUPAC name for the following structure: 3-chloro-6-methylcyclohexanol 2-methyl-5-chlorocyclohexanol 1-chloro-4-methylcy

Shtirlitz [24]

Answer:

5-chloro-2-methylcyclohexanol

Explanation:

There is no structure for the compound, but we can analyze the proposed options using the IUPAC rules to name organic compounds.

IUPAC rules state that to name an organic compound, first we have to identify the priorities for the functional groups present in the compound. In this case, the priority functional group is the alcohol group, so we will start the counting of the carbons in this group. Then, the counting of carbon atoms is followed by the next substituents so they have the lowest possible numbers, in this case, we can assign the number 2 to the methyl group and 5 to the chloride group, and name the compound in alphabetical order, using commas to separate the words from the numbers and with no space between the words.

Since the other options involve: high countings for the susbtituents groups (3-chloro-6-methylcyclohexanol), wrong assignation of priority functional group (1-chloro-4-methylcyclohexanol), wrong sequence of counting in the compound (2-methyl-3-chlorocyclohexanol) and no alphabetical order to name the compound (2-methyl-5-chlorocyclohexanol), the correct option is:

5-chloro-2-methylcyclohexanol

Have a nice day!

4 0

3 years ago

3. A measurement of the freezing temperature of a solution allowsyou to calculate the concentration of the solution. What else d

Harman [31]

Answer:

Osmotic pressure and boiling point elevation

Explanation:

In the the osmotic pressure one can determine the molar mass of a solid by calculating the number of moles from the Morality formula which involves the volume of the solution.

In the boiling point elevation you can determine the number of moles of the solute in the solution by using the Molality formula.

5 0

2 years ago