Question

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The standard molar enthalpy of combustion of ethane (C2Helgy) is -1559 7 KJ mor 1. Which energy diagram corresponds to this process? Enthalpy 1559 Reaction coordinate 3559 Reaction coordinate Enthalpy -1559 Reaction coordinate Enthalpy -1559

Answer 1

13) Given that

Volume of NaOH solution to be made, V = 425.00mL = 0.425L

Molarity of the solution to be made, M = 0.100 M

We know that,

$\small \textup{Molarity }=\frac{\textup{no of moles of NaOH }}{\textup{Volume of the soln}}$

No of moles = Molarity × Volume

= 0.100 × 0.425

= 0.0425 moles NaOH

Molar mass of NaOH = 40 g/mol

Therefore, Mass of NaOH

= no of moles × Molar mass

= 0.0425 × 40

= 1.7 grams of NaOH

14) The reaction between hydrochloric acid and barium hydroxide is

$\small 2HCl+Ba(OH)_2\rightarrow 2H_2O +BaCl_2$

Molarity of HCl solution = 0.146 M

Volume of HCl soln = 28.12 mL = 0.02812 L

No of moles of HCl = 0.146 × 0.02812 = $\small 4.11*10^{-3}$ moles

2 mol HCl require 1 mol of Barium hydroxide (Ba(OH)2)

Therefore $\small 4.11*10^{-3}$ mol of HCl require :-

1 * 4.11 * 10-3 2.05 * 10-3 moles Ba(OH)2 2

Given that, volume of $\small Ba(OH) _2$ = 25.00 mL = 0.025 L

Therefore Molarity of $\small Ba(OH) _2$

$\small \textup{Molarity }=\frac{2.05*10^{-3}moles}{0.025\textup{ L}}= 0.082 \textup{ M}$

15) In the redox reaction,

$\small Fe_2O_3+3CO\rightarrow 2Fe+3CO_2$

Here iron is reduced and the reducing agent is CO

Explanation :-

If an chemical species gain electrons and charge is decreased, the process is called reduction and it is said that the species is reduced. A reducing agent is a chemical species which is oxidized (or lose electrons)

Here the Fe in $\small Fe$ in $\small Fe_2O_3$ has a charge of +3 and it gain electrons and reduced to charge of 0 in Fe.

C in CO has a charge of +2. It lose electrons and attain +4 charge in CO2, therefore CO is reducing agent

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