Chem 141_0076 Spring 2018- Exam 2- April 13th 10. The following reaction is used

Question

Chem 141_0076 Spring 2018- Exam 2- April 13th 10. The following reaction is used to generate hydrogen gas in the laboratory. If243 mL of gas is collected at 25°C and has a total pressure of 745 mm Hg, what mass of hydrogen is produced? A table of water vapor pressures is provided. Mg(s) + 2 HCIa?) MgCl2(ag)+H2(2) TCC) P(mm Hg 17.55 23.78 31.86 20 a. 0.0144 g H2 b.0.0449 g H2 c. 0.0190 g H2 d. 0.0196 g H2 e. 0.0717 g H2 11. Which of the following statements is not true of a redox reaction? a. The substance oxidized loses electrons. b. The reducing agent gains electrons. c. The reducing agent is the substance oxidized. d. The oxidizing agent is the substance reduced. e. none of the above 12. Identify the missing words (or phrases) in the following definition: "An oxidation when the electrons in each bond number is the it is participating in are assigned to the atoms involved in the bond." a. number of electrons, appears to have, less b. number of electrons, definitely has, more c. charge, appears to have, more d. charge, definitely has, less that an atom el 13. In the following reaction H2S04 is H2S04 + HI 12+S02+ H20 a. the oxidizing agent and is oxidized b. the oxidizing agent and is reduced c. the reducing agent and is reduced d. the reducing agent and is oxidized e, none of the above

Explanation / Answer

10)

We know the equation of gas equation :

PV=nRT

P=745mmHg or (745/760) atm

T= 25 degree or 273+25 = 298k

V= 243ml or .243L

R= gas constant= 0.082 atm

Putting all the values in the equation PV=nRT

We get the value of n= (.238÷24.436) mole of hydrogen

So In 1 mole 2 gm hydrogen is present

So in mass of hydrogen =(.238÷24.436)×2=0.0196 g of hydrogen

So option (c) is right

11) reducing agents are those who loose electrons or oxidised

So answer is (b )which is wrong about redox reaction

12) oxidation no is the charge appears on the atom

When forms bond with the more electronegative atom

So answer no (c )is right

13)

Here sulphuric acid is reduced to SO2 so sulphuric acid is oxidising agent and reduced to SO2

Hence option (b) is right

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