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3 years ago

(05.06 LC)

Chemistry

1 answer:

goblinko [34]3 years ago

5 0

Answer:

Explanation:

because percentage yield =actual/theoretical yield

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How many grams of sodium fluoride should be added to 300. mL of 0.0310 M of hydrofluoric acid to produce a buffer solution with

Kisachek [45]

Answer : The mass of sodium fluoride added should be 0.105 grams.

Explanation : Given,

The dissociation constant for HF = $K_a=6.8\times 10^{-4}$

Concentration of HF (weak acid)= 0.0310 M

First we have to calculate the value of $pK_a$ .

The expression used for the calculation of $pK_a$ is,

$pK_a=-\log (K_a)$

Now put the value of $K_a$ in this expression, we get:

$pK_a=-\log (6.8\times 10^{-4})$

$pK_a=4-\log (6.8)$

$pK_a=3.17$

Now we have to calculate the concentration of NaF.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[NaF]}{[HF]}$

Now put all the given values in this expression, we get:

$2.60=3.17+\log (\frac{[NaF]}{0.0310})$

$[NaF]=0.00834M$

Now we have to calculate the moles of NaF.

$\text{Moles of NaF}=\text{Concentration of NaF}\times \text{Volume of solution}=0.00834M\times 0.300L=0.0025mole$

Now we have to calculate the mass of NaF.

$\text{Mass of }NaF=\text{Moles of }NaF\times \text{Molar mass of }NaF=0.0025mole\times 42g/mole=0.105g$

Therefore, the mass of sodium fluoride added should be 0.105 grams.

4 0

4 years ago

Equal but opposite forces acting on an object results in what?

forsale [732]

Answer:

Action given and reaction taken

Also known as

Newton's third law of motion

Explanation:

An action will be done such as bouncing a ball on the wall

- You throw the ball (Action)

- The ball bounces back (Reaction)

Hope this Helps

3 0

3 years ago

Certain metal oxide has the formula MO where M denotes the metal. A 73.35−g sample of the compound is strongly heated in an atmo

pshichka [43]

Answer:

atomic mass 112.4 and Cadmium (Cd)

Explanation:

You have 73.35 g of MO.

After the reaction the O is removed and you only have M which the mass is 64.21 g.

With that you can calculate the mass of O removed:

Mass of O = 9.14 g

Mass = AM * moles ; (AM : Atomic Mass)

9.14 = 16 * moles

moles = 9.14 / 16

moles = 0.57125

The formula of the metal oxide is MO, meaning it has 1 mole of M per mole of O. 73.35 had 0.57125 moles of O, then it also had 0.57125 moles of M, and the remaining mass of 64.21 g represents those moles

Mass = AM * moles ; (AM : Atomic Mass)

64.21 = AM * 0.57125

AM = 64.21/0.57125 = 112.4 amu

The metal with an atomic mass of 112.4 is Cadmium (Cd), therefore the metal oxide is CdO

7 0

3 years ago

How many particles would be in 0.5 moles?

harkovskaia [24]

Answer:

3.011 × 10²³ particles

Explanation:

Given data:

Number of moles = 0.5 mol

Number of particles = ?

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

one mole of substance = 6.022 × 10²³ particles

For 0.5 mole of substance:

0.5 mol × 6.022 × 10²³ particles / 1 mol

3.011 × 10²³ particles

8 0

3 years ago

What role does potassium iodide play in generating oxygen

Zielflug [23.3K]

Potassium iodide will act as the catalyst to decompose hydrogen peroxide into water and oxygen. A catalyst is a substance that participates in a chemical reaction and influences its speed without undergoing permanent change.<span>

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7 0

4 years ago