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Ganezh [65]
3 years ago
14

A solution was made by adding water to 0.250 g of H2Z until the volume totaled 25.00 mL. Subsequent titration required 40.50 mL

of 0.100 M sodium hydroxide. Calculate the molar mass of H2Z (in g/mol).
given: H2Z(aq) + 2 NaOH(aq) → Na 2Z(aq) + 2 H2O(ℓ)
Chemistry
1 answer:
Brilliant_brown [7]3 years ago
7 0

Answer:

123 g/mol

Explanation:

Let's consider the neutralization reaction.

H₂Z(aq) + 2 NaOH(aq) → Na₂Z(aq) + 2 H₂O(ℓ)

The moles of NaOH that reacted are:

40.50 \times 10^{-3} L \times \frac{0.100molNaOH}{1L} =4.05\times 10^{-3} molNaOH

The molar ratio of H₂Z to NaOH is 1:2. The moles of H₂Z that reacted are:

4.05\times 10^{-3} molNaOH \times \frac{1molH_{2}Z}{2molNaOH} =2.03\times 10^{-3} molH_{2}Z

The molar mass of H₂Z is:

\frac{0.250gH_{2}Z}{2.03\times 10^{-3} molH_{2}Z} =123g/mol

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[H_{3}O^{+}] = 0.00770 M

The equilibrium equation representing the dissociation of FCH_{2}COOH

FCH_{2}COOH(aq) + H_{2}O (l)    FCH_{2}COO^{-}(aq)+ H_{3}O^{+}(aq)

Given [H_{3}O^{+}] = 0.00770 M

Let the initial concentration of acid be x and change y

So y = [H_{3}O^{+}] =[FCH_{2}COO^{-}] = 0.00770 M

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7 0
4 years ago
Calculate the average atomic mass of Mg if the naturally occurring isotopes are Mg - 24, Mg - 25 and Mg - 26. Their masses and a
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24.309

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5 0
1 year ago
8. A sample of potassium chlorate (KCIO,) was heated in a test tube and decomposed 2KC?(s) 302 (g) + 2KCIO, (s) The oxygen was c
dangina [55]

Answer:

Partial pressure of O_{2} in the gas was 733 torr and mass of KClO_{3} in the sample was 2.12 g.

Explanation:

a) Total pressure of gas = (partial pressure of water vapour)+(partial pressure of O_{2})

Here partial pressure of water vapour is 21 torr and total pressure of gas is 754 torr.

So, partial pressure of O_{2}= (total pressure of gas)-(partial pressure of water vapour) = (754 torr) - (21 torr) = 733 torr

b) Lets assume that O_{2} behaves ideally. Hence-

                                            PV=nRT

where P is pressure of O_{2}, V is volume of O_{2} , n is number of moles of O_{2} , R is gas constant and T is temperature in kelvin

here P = 733 torr = (733\times 0.001316)atm = 0.9646 atm

        V = 0.65 L, R = 0.082 L.atm/(mol.K), T=(273+22)K = 295 K

   So, n=\frac{PV}{RT}

                   = \frac{(0.9646 atm)\times (0.65 L)}{(0.082 L.atm/(mol.K))\times (295 K)}

                   = 0.0259 moles

As 3 moles of O_{2} are produced from 2 moles of KClO_{3} therefore 0.0259 moles of O_{2} are produced from (\frac{2\times 0.0259}{3}) moles or 0.0173 moles of KClO_{3}.

Molar mass of KClO_{3}= 122.55 g

So mass of KClO_{3} in sample = (0.0173\times 122.55)g

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