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3 years ago

Given the balanced equation: 4Fe(s) + 30₂(g) → 2Fe₂O₃(s) + 1640 kJ Which phrase best describes this reaction?

Chemistry

1 answer:

Troyanec [42]3 years ago

3 0

Answer:

yeah the answer under the explanation

Explanation:

The answer is (4) exothermic with ΔH = -1640 kJ. The 1640 kJ energy is at the right side of equation means that it releases energy. The enthalpy change means the energy of production minus the energy of reactants. If it is exothermic, the ΔH < 0.

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Calculate the empirical formula for each stimulant based on its elemental mass percent composition. a. nicotine (found in tobacc

Ira Lisetskai [31]

This an incomplete question, here is a complete question.

Calculate the empirical formula for each stimulant based on its elemental mass percent composition.

a. nicotine (found in tobacco leaves): C 74.03%, H 8.70%, N 17.27%

b. caffeine (found in coffee beans): C 49.48%, H 5.19 %, N 28.85% and O 16.48%

Answer:

(a) The empirical formula for the given compound is $C_5H_7N$

(b) The empirical formula for the given compound is $C_4H_5N_2O$

Explanation:

Part A: nicotine

We are given:

Percentage of C = 74.03 %

Percentage of H = 8.70 %

Percentage of N = 17.27 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 74.03 g

Mass of H = 8.70 g

Mass of N = 17.27 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{74.03g}{12g/mole}=6.17moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{8.70g}{1g/mole}=8.70moles$

Moles of Nitrogen = $\frac{\text{Given mass of nitrogen}}{\text{Molar mass of nitrogen}}=\frac{17.27g}{14g/mole}=1.23moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 1.23 moles.

For Carbon = $\frac{6.17}{1.23}=5.01\approx 5$

For Hydrogen = $\frac{8.70}{1.23}=7.07\approx 7$

For Nitrogen = $\frac{1.23}{1.23}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : N = 5 : 7 : 1

The empirical formula for the given compound is $C_5H_7N_1=C_5H_7N$

Part B: caffeine

We are given:

Percentage of C = 49.48 %

Percentage of H = 5.19 %

Percentage of N = 28.85 %

Percentage of O = 16.48 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 49.48 g

Mass of H = 5.19 g

Mass of N = 28.85 g

Mass of O = 16.48 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{49.48g}{12g/mole}=4.12moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{5.19g}{1g/mole}=5.19moles$

Moles of Nitrogen = $\frac{\text{Given mass of nitrogen}}{\text{Molar mass of nitrogen}}=\frac{28.85g}{14g/mole}=2.06moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{16.48g}{16g/mole}=1.03moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 1.03 moles.

For Carbon = $\frac{4.12}{1.03}=4$

For Hydrogen = $\frac{5.19}{1.03}=5.03\approx 5$

For Nitrogen = $\frac{2.06}{1.03}=2$

For Nitrogen = $\frac{1.03}{1.03}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : N : O = 4 : 5 : 2 : 1

The empirical formula for the given compound is $C_4H_5N_2O_1=C_4H_5N_2O$

6 0

3 years ago

What is the wavelength, in nm, of the light photon emitted by a hydrogen atom when an electron goes from n

xxMikexx [17]

Answer:

Hence, the wavelength of the photon associated is 1282 nm.

Explanation:

8 0

3 years ago

A(n) ____________________ has a rectangular shape and contains a cell wall, chloroplasts, and one large vacuole.

tiny-mole [99]

I’m pretty sure the answer is “plant cell”

7 0

3 years ago

Aqueous sulfuric acid (H2SO4) reacts with solid sodium hydroxide (NaOH) to produce aqeous sodium sulfate (Na2SO4) and liquid wat

Montano1993 [528]

Answer:

The theoretical yield of water formed is 2.2 grams

Explanation:

Step 1: Data given

Mass of H2SO4 = 5.9 grams

Mass of NaOH = 6.6 grams

Molar mass H2SO4 = 98.08 g/mol

Molar mass of NaOH = 40.0 g/mol

Step 2: The balanced equation

2NaOH + H2SO4 → Na2SO4 + 2H2O

Step 3: Calculate moles

Moles = mass / molar mass

Moles H2SO4 = 5.9 grams / 98.08 g/mol

Moles H2SO4 = 0.060 moles

Moles NaOH = 6.6 grams / 40.0 g/mol

Moles NaOH = 0.165 moles

Step 4: Calculate the limiting reactant

For 2 moles NaOH we need 1 mol H2SO4 to produce 1 mol Na2SO4 and 2 moles H2O

H2SO4 is the limiting reactant. It will completely be consumed ( 0.060 moles). NaOH is in excess . There will react 2*0.060 = 0.120 moles

There will remain 0.165 - 0.120 = 0.045 moles NaOH

Step 5: Calculate moles H2O

For 2 moles NaOH we need 1 mol H2SO4 to produce 1 mol Na2SO4 and 2 moles H2O

For 0.0600 moles H2SO4 we'll have 2*0.0600 = 0.120 moles H2O

Step 6: Calculate mass H2O

Mass H2O = 0.120 moles * 18.02 g/mol

Mass H2O = 2.16 grams

The theoretical yield of water formed is 2.2 grams

4 0

3 years ago

How much energy is released when 20.0 g of water is cooled from 50°C to 30°C (Cwater= 4.18 J/ g*°C)

marissa [1.9K]

Answer:

1672 J

Explanation:

We are supposed to find out the energy released by water when cooled from 50° C to 30°C .

We have the relation that ,

H=msΔT

Information is given that s=4.18 J/ g*°C ,

m=20.0 g,

and ΔT is -20° C.

Hence by substituting we get,

H=-20*20*4.18

(minus symbol represents that energy is being released)

1672 J is release when water is cooled from 50° C to 30°C .

7 0

3 years ago