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3 years ago

A phosphate buffer is prepared with KH2PO4 at 0.02 M and K2HPO4 at 0.03 M. What is the concentration of phosphate buffer

Chemistry

1 answer:

Alona [7]3 years ago

6 0

Answer:

0.05M is the concentration of the phosphate buffer

Explanation:

A buffer is defined as the aqueous mixture of a weak acid (KH₂PO₄) and its conjugate base (K₂HPO₄). The concentration of this buffer is the sum of the concentrations of the weak acid and the conjugate base, that is:

Concentration of phosphate buffer = 0.02M + 0.03M

<h3>0.05M is the concentration of the phosphate buffer</h3>

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For the following reaction, 4.07 grams of aluminum oxide are mixed with excess sulfuric acid. The reaction yields 10.4 grams of

torisob [31]

Answer:

Theoretical yield = 13.7 g

% yield =76 %

Explanation:

For $Al_2O_3$

Mass of $Al_2O_3$ = 4.07 g

Molar mass of $Al_2O_3$ = 101.96 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{4.07\ g}{101.96\ g/mol}$

$Moles\ of\ Al_2O_3= 0.0399\ mol$

According to the reaction:

$Al_2O_3+3H_2SO_4\rightarrow Al_2(SO_4)_3+3H_2O$

1 mole of $Al_2O_3$ on reaction produces 1 mole of $Al_2(SO_4)_3$

So,

0.0399 mole of $Al_2O_3$ on reaction produces 0.0399 mole of $Al_2(SO_4)_3$

Moles of $Al_2(SO_4)_3$ obtained = 0.0399 mole

Molar mass of $Al_2(SO_4)_3$ = 342.2 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$0.0399= \frac{Mass}{342.2\ g/mol}$

$Mass= 13.7\ g$

<u>Theoretical yield = 13.7 g</u>

The expression for the calculation of the percentage yield for a chemical reaction is shown below as:-

$\%\ yield =\frac {Experimental\ yield}{Theoretical\ yield}\times 100$

Given , Values from the question:-

Theoretical yield = 13.7 g

Experimental yield = 10.4 g

Applying the values in the above expression as:-

$\%\ yield =\frac{10.4}{13.7}\times 100$

<u>% yield =76 %</u>

6 0

3 years ago

How many atoms are there in 3.559*10^-6 mol of krypton?

algol [13]

Answer:

The answer is

<h2> $2.143 \times {10}^{18} \: \: atoms$ </h2>

Explanation:

To find the number of atoms given the number of moles we use the formula

N = n × L

where

N is the number of entities

n is the number of moles

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question

$n = 3.559 \times {10}^{ - 6} \: mol$

Substitute the values into the above formula and solve

That's

<h3> $N = 3.559 \times {10}^{ - 6} \times 6.02 \times {10}^{23} \\ = 2.1425 \times {10}^{18}$ </h3>

We have the final answer as

<h3> $N = 2.143 \times {10}^{18} \: \: atoms$ </h3>

Hope this helps you

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4 years ago

A 20 N object is placed on a surface and starts to slide. What is the MOST likely reason the object begins to move?

ra1l [238]

Answer:

Explanation:

If the object starts to slide it must be on a slope.

There are 2 forces acting on the object - gravity and the friction between the object and the surface.

If sliding starts then the forces must be unbalanced.

The force of gravity is greater than the friction.

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3 years ago

What is the Gibbs free energy?

Dimas [21]

It's a thermodynamic quantity equal to the enthalpy minus the product of entropy and the absolute temperature

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4 years ago

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Disposal site for solid waste

Alexxandr [17]

Answer:

"where deliberately discarded solid waste is discharged, deposited, injected, dumped, spilled, leaked, or placed so that such solid waste or a constituent thereof may enter the environment or be emitted into the air or discharged into waters, including ground waters."

Explanation:

https://definitions.uslegal.com/s/solid-waste-disposal-site/

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3 years ago