Which of the following values are not equal to 1 mole

Which of the following is not a reason why actual yield is less than theoretical yield?

Gnom [1K]

Your answer is B, conservation of mass

Recall that percent yield is given by: %Yeild = actual yeild/theoretical yeild x100

During experiments, there are errors made:

• uncertainty in measurements

• losses of reactants and products

• impurity in reactants

• losses during separation (e.g. filtration or purification)

• Some side reactions might also happen.

Among the given options, only conservation of mass does not contribute to a lower actual yield compared to the theoretical yield.

5 0

3 years ago

In the laboratory, a general chemistry student measured the pH of a 0.486 M aqueous solution of triethanolamine, C6H15O3N to be

STatiana [176]

Answer:

Kb = 6.22x10⁻⁷

Explanation:

Triethanolamine, C₆H₁₅O₃N, is in equilibrium with water:

C₆H₁₅O₃N(aq) + H₂O(l) ⇄ C₆H₁₅O₃NH⁺(aq) + OH⁻(aq)

Kb is defined from concentrations in equilibrium, thus:

Kb = [C₆H₁₅O₃NH⁺] [OH⁻] / [C₆H₁₅O₃N]

The equilibrium concentration of these compounds could be written as:

[C₆H₁₅O₃N] = 0.486M - X

[C₆H₁₅O₃NH⁺] = X

[OH⁻] = X

pH is -log [H⁺], thus, [H⁺] = 10^-pH = 1.820x10⁻¹¹M

Also, Kw = [OH⁻] ₓ [H⁺];

1x10⁻¹⁴ = [OH⁻] ₓ [H⁺]

1x10⁻¹⁴ = [OH⁻] ₓ [1.820x10⁻¹¹M]

5.495x10⁻⁴M = [OH⁻], that means <em>X = 5.495x10⁻⁴M</em>

Replacing in Kb formula:

Kb = [5.495x10⁻⁴M] [5.495x10⁻⁴M] / [0.486M-5.495x10⁻⁴M]

5 0

3 years ago

You were rushing to get to school on time and dropped your breakfast food! Choose one atom in that food item and explain the sto

OLga [1]

Answer:

I am going to chose your apple on your breakfast plate. Somebody plantes the apple seed. The apple tree takes time to grow. Once the apples are ready to be picked they are picked. Then the apples are sorted and go off to different schools like your school. Which is where you pick the apple up and put it on your plate.

Explanation:

3 0

3 years ago

Calculate the heat energy required to melt 4kg of ice when the specific latent heat of fusion of water is 334,000 J/kg.

Setler79 [48]

Taking into account the definition of calorimetry and latent heat, the heat energy required to melt 4 kg of ice when the specific latent heat of fusion of water is 334,000 $\frac{J}{kg}$ is 1,336 kJ.

<h3>Calorimetry</h3>

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

<h3>Latent heat</h3>

Latent heat is defined as the energy required by a quantity of substance to change state.

When this change consists of changing from a solid to a liquid phase, it is called heat of fusion and when the change occurs from a liquid to a gaseous state, it is called heat of vaporization.

The heat Q that is necessary to provide for a mass m of a certain substance to change phase is equal to

Q = m×L

where L is called the latent heat of the substance and depends on the type of phase change.

<h3>Heat energy required to melt ice</h3>

In this case, you know:

m= 4 kg
L= specific latent heat of fusion of water= 334,000 $\frac{J}{kg}$

Replacing in the expression for latent heat:

Q = 4 kg× 334,000 $\frac{J}{kg}$

Solving:

<u><em>Q= 1,336,000 J= 1,336 kJ </em></u>(being 1,000 J= 1 kJ)

Finally, the correct answer is the first option: the heat energy required to melt 4 kg of ice when the specific latent heat of fusion of water is 334,000 $\frac{J}{kg}$ is 1,336 kJ.

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7 0

2 years ago

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After two half-lives, a sample contains 10 grams of parent isotopes. How many grams of the parent isotope were present to start?

Lunna [17]