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3 years ago

What is the role of an indicator during a titration?

Chemistry

1 answer:

Hatshy [7]3 years ago

4 0

Answer:

The role of indicator in titration is to detect the endpoint of the titration.

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Which of the following is an example of a compound?

VladimirAG [237]

Answer:

H2O is a compound because its a main constitute of earths hydrosphere

3 0

2 years ago

Which one has a greatest mass, one atom of carbon, one atom of hydrogen, or one atom of litium

SpyIntel [72]

Lithium, it has an atomic number of about 3

5 0

3 years ago

At 25 °C, how many dissociated OH– ions are there in 1243 mL of an aqueous solution whose pH is 2.07?

coldgirl [10]

<u>Answer:</u> The number of $OH^-$ ions dissociated are $8.57\times 10^{11}$

<u>Explanation:</u>

We are given:

pH = 2.07

Calculating the value of pOH by using equation, we get:

$2.07+pOH=14\\\\pOH=14-2.07=11.93$

To calculate hydroxide ion concentration, we use the equation to calculate pOH of the solution, which is:

$pOH=-\log[OH^-]$

We are given:

pOH = 11.93

Putting values in above equation, we get:

$11.93=-\log[OH^-]$

$[OH^-]=10^{-11.93}=1.17\times 10^{-12}M$

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

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

Molarity of solution = $1.17\times 10^{-12}M$

Volume of solution = 1243 mL = 1.243 L (Conversion factor: 1 L = 1000 mL)

Putting values in above equation, we get:

$1.17\times 10^{-12}M=\frac{\text{Moles of }OH^-}{1.243L}\\\\\text{Moles of }OH^-=(1.17\times 10^{-12}mol/L\times 1.243L)=1.424\times 10^{-12}mol$

According to mole concept:

1 mole of a compound contains $6.022\times 10^{23}$ number of particles

So, $1.424\times 10^{-12}mol$ number of $OH^-$ will contain = $(1.424\times 10^{-12}\times 6.022\times 10^{23})=8.57\times 10^{11}$ number of ions

Hence, the number of $OH^-$ ions dissociated are $8.57\times 10^{11}$

3 0

3 years ago

Which of the following best summarizes the ideal gas law?

8090 [49]

Answer:

Option C. PV = nRT

Explanation:

The ideal gas gas equation gives the relationship between pressure, volume, number mole a gas and temperature of gas.

Mathematically, the ideal gas equation is given as:

PV = nRT

Where:

P is the pressure measured in atmosphere (atm).

V is the volume measured in litres(L) or cubic decimetre (dm³).

n is the number of mole of gas.

R is the gas constant (0.0821atm.L/Kmol)

T is temperature measured in Kelvin (K).

4 0

3 years ago

On the basis of the information above, a buffer with a pH = 9 can best be made by using

telo118 [61]

Answer:

D H2PO4– + HPO42–

Explanation:

The acid dissociation constant for $\mathbf{H_3PO_4 , H_2PO^{-}_4 , HPO_4^{2-}}$ are $\mathbf{7\times 10^{-3}, \ \ 8\times 10^{-8} ,\ \ 5\times 10^{-13}}$ respectively.

$\mathbf{pka (H_3PO_4) = -log (7\times 10^{-3} )=2.2}$

$\mathbf{pka (H_2PO_4^-) = -log (8\times 10^{-8} )=7.1}$

$\mathbf{pka (HPO_4^{2-}) = -log (5\times 10^{-13} )=12.3}$

The reason while option D is the best answer is that, the value of pKa for both

$\mathbf{H_2PO^{-}_4 ,\ \& \ HPO_4^{2-}}$ lies on either side of the desired pH of the buffer. This implies that one is slightly over and the other is slightly under.

Using Henderson-Hasselbach equation:

$\mathbf{pH = pKa + log \Big( \dfrac{HPO_4^{2-}}{H_2PO_4^-} \Big)}$

3 0

2 years ago