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4 years ago

Write the acidic equilibrium equation for HPO42

Chemistry

1 answer:

ahrayia [7]4 years ago

5 0

Explanation:

$HPO_4^{2-}$ is a conjugate base of $H_2PO_4^{-}$ but it has one acidic hydrogen which dissociates in the solution and exists in the equilibrium as shown below:

$HPO_4^{2-}+H_2O\rightleftharpoons H_3O^++PO_4^{3-}$

The expression for the dissociation constant, $K_a$ for $HPO_4^{2-}$ is shown below as:

$K_a=\frac {[H_3O^+][PO_4^{3-}]}{[HPO_4^{2-}]}$

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A titration graph shows little resistance to a change in pH at the start and has a single equivalence point of 8.6.

konstantin123 [22]

Answer: A weak acid titrated by a strong base

Explanation:

The graph refers to the titration of a weak acid such as Hydrofluoric acid with a strong base such as Sodium Hydoxide. What happens is that as the process begins, the pH rises quickly as there is little resistance to the base.

After some time the solution formed begins to act as a buffer between the remaining acid and the base. This reduces the pH change rate and will continue until the base overcomes the solution's buffering capacity.

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3 years ago

A 0.708 g sample of a metal, M, reacts completely with sulfuric acid according to the reaction M ( s ) + H 2 SO 4 ( aq ) ⟶ MSO 4

ollegr [7]

Answer:

The metal has a molar mass of 65.37 g/mol

Explanation:

Step 1: Data given

Mass of the metal = 0.708 grams

Volume of hydrogen = 275 mL = 0.275 L

Atmospheric pressure = 1.0079 bar = 0.9947 atm

Temperature = 25°C

Vapor pressure of water at 25 °C = 0.03167 bar = 0.03126 atm

Step 2: The balanced equation

M(s) + H2SO4(aq) ⟶ MSO4 (aq) + H2(g)

Step 3: Calculate pH2

Atmospheric pressure = vapor pressure of water + pressure of H2

0.9947 atm = 0.03126 atm + pressure of H2

Pressure of H2 = 0.9947 - 0.03126

Pressure of H2 = 0.96344 atm

Step 4: Calculate moles of H2

p*V=n*R*T

⇒ with p = The pressure of H2 = 0.96344 atm

⇒ with V = the volume of H2 = 0.275 L

⇒ with n = the number of moles H2 = TO BE DETERMINED

⇒ with R = the gas constant = 0.08206 L*atm/K*mol

⇒ with T = the temperature = 25°C = 298 Kelvin

n = (p*V)/(R*T)

n = (0.96344 * 0.275)/(0.08206*298)

n = 0.01083 moles

Step 5: Calculate moles of M

For 1 mole of H2 produced, we need 1 mole M

For 0.0108 moles of H2 we need 0.01083 moles of M

Step 6: Calculate molar mass of M

Molar mass M = Mass M / moles M

Molar mass M = 0.708 grams / 0.01083 moles

Molar mass M = 65.37 g/mol

The metal has a molar mass of 65.37 g/mol

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Answer:

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