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  1. Asked: 3 years agoIn:

    Methanol (CH3OH) burns according to the equation

    2CH3OH(l) + 3O2(g) → 2CO2(g) + 4H2O(l), ΔH°rxn = –1454 kJ/mol.

    How much heat, in kilojoules, is given off when 75.0 g of methanol is burned?

    (A) 727 kJ

    (B) 3.22 x 103 kJ

    (C) 1.45 x 103 kJ

    (D) 1.70 x 10–3 kJ

    (E) 3.41 x 103 kJ

    0bffe

    (D) 1.70 x 10–3 kJ

    (D) 1.70 x 10–3 kJ

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  2. Asked: 3 years agoIn:

    the enthalpy change for the reaction C3H8 + H2 =C2H6 + CH4 at 25*c is 55.7 kj/mole Calculate the heat of combusition of C2H6 .the heat of combustion of H2.CH4,C[graphite] are -285.8   , -890.0 , -393.5 kj/mole respestevily . Heat of combustion of propani is -2240 kj/mole

    a67a3

    Given C3H8 + H2 =C2H6 + CH4,           ΔH1= + 55.7 kJ/moleH2+1/2O2 =H2O,                      ΔH2= -285.8 kJ/moleCH4+2O2 =CO2+2H2O,           ΔH3= -890.0 kJ/moleC(graphite)+O2 =CO2,             ΔH4= -393.5 kJ/moleC3H8 +5 O2 =3 CO2+4H2O,    ΔH5=  -2240 kJ/molewe are to measure C2H6 +7/2 O2 =2CO2+3H2ORead more

    Given

    C3H8 + H2 =C2H6 + CH4,           ΔH1= + 55.7 kJ/mole

    H2+1/2O2 =H2O,                      ΔH2= -285.8 kJ/mole

    CH4+2O2 =CO2+2H2O,           ΔH3= -890.0 kJ/mole

    C(graphite)+O2 =CO2,             ΔH4= -393.5 kJ/mole

    C3H8 +5 O2 =3 CO2+4H2O,    ΔH5=  -2240 kJ/mole

    we are to measure

    C2H6 +7/2 O2 =2CO2+3H2O,   ΔH6= ?  kJ/mole

    So

    ΔH6 = ΔH5– ΔH1 +   ΔH2 –   ΔH3

    = -2240– 55.7 +   (-285.8)  -(-890.0)

    = -1691.5 kJ/mole

     

     

     

     

     

     

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  3. Asked: 3 years agoIn:

    Suppose a 50.0 g block of silver (specific heat = 0.2350 J/g·°C) at 100°C is placed in contact with a 50.0 g block of iron (specific heat = 0.4494 J/g·°C) at 0°C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocks 

    (A) will be higher than 50°C. 

    (B) will be lower than 50°C. 

    (C) will be exactly 50°C. 

    (D) is unrelated to the composition of the blocks. 

    (E) cannot be predicted.

    f796e

    (B) will be lower than 50°C.

    (B) will be lower than 50°C.

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  4. Asked: 3 years agoIn:

    For which of these reactions will the difference between ΔH° and ΔE° be the smallest? 

    (A) N2(g) + 3H2(g) → 2NH3(g) 

    (B) 4PH3(g) → P4(g) + 6H2(g) 

    (C) H2(g) + Cl2(g) → 2HCl(g) 

    (D) CO2(g) + 2H2O(l) → CH4(g) + 2O2(g) 

    (E) P4(s) + 10Cl2(g) → 4PCl5(s)

    e3448

    (C) H2(g) + Cl2(g)→ 2HCl(g)

    (C) H2(g) + Cl2(g)→ 2HCl(g)

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  5. Asked: 3 years agoIn:

    The heat of solution of ammonium nitrate is 26.2 kJ/mol. If a 5.368 g sample of NH4NO3 is added to 40.0 mL of water in a calorimeter at 23.5°C, what is the minimum temperature reached by the solution? (The specific heat of water = 4.18 J/g·°C; the heat capacity of the calorimeter = 650. J/°C.) 

    (A) 14.3°C 

    (B) 20.8°C 

    (C) –7.7°C 

    (D) 25.6°C 

    (E) 21.4°C

    ec0b9

    The Correct option is (E) 21.4°C

    The Correct option is (E) 21.4°C

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  6. Asked: 3 years agoIn:

    At 25°C, the following heats of reaction are known: 

    2ClF(g) + O2(g) → Cl2O(g) + F2O(g ΔH°rxn = 167.4 kJ/mol

    2ClF3(g) + 2O2(g) → Cl2O(g) + 3F2O(g) ΔH°rxn = 341.4 kJ/mol

    2F2(g) + O2(g) → 2F2O(g) ΔH°rxn = –43.4 kJ/mol

    At the same temperature, use Hess’s law to calculate ΔH°rxn for the reaction:

    ClF(g) + F2(g) → ClF3(g)

    (A) –217.5 kJ/mol

    (B) –130.2 kJ/mol

    (C) 217.5 kJ/mol

    (D) –108.7 kJ/mol

    e1ee0

    (D) –108.7 kJ/mol

    (D) –108.7 kJ/mol

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  7. Asked: 3 years agoIn:

    Glycine, C2H5O2N, is important for biological energy. The combustion reaction of glycine is given by the equation

    4C2H5O2N(s) + 9O2(g) →8CO2(g) + 10H2O(l) + 2N2(g) ΔH°rxn = –3857 kJ/mol

    Given that DH°f[CO2(g)] = –393.5 kJ/mol and ΔH°f[H2O(l)] = –285.8 kJ/mol, calculate the enthalpy of formation of glycine.

    (A) –537.2 kJ/mol

    (B) –268.2 kJ/mol

    (C) 2,149 kJ/mol

    (D) –3,178 kJ/mol

    (E) –964 kJ/mol 

    2891a

    (A) –537.2 kJ/mol

    (A) –537.2 kJ/mol

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  8. Asked: 3 years agoIn:

    Given that CaO(s) + H2O(l) →Ca(OH)2(s), ΔH°rxn = –64.8 kJ/mol, how many grams of CaO must react in order to liberate 525 kJ of heat? 

    (A) 6.92 g 

    (B) 56.1 g 

    (C) 455 g 

    (D) 606 g 

    (E) 3.40 x 104 g

    cf678

    The Correct option is (C) 455 g

    The Correct option is (C) 455 g

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  9. Asked: 3 years agoIn:

    If 325 g of water at 4.2°C absorbs 12.28 kJ, what is the final temperature of the water? The specific heat of water is 4.184 J/g·°C. 

    (A) 4.21°C 

    (B) 4.8°C 

    (C) 9.0°C 

    (D) 13.2°C 

    (E) 2,938°C

    1b7c5

    The Correct option is (D) 13.2°C

    The Correct option is (D) 13.2°C

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  10. Asked: 3 years agoIn:

    Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data: heat of combustion of C2H4(g) = –1411 kJ/mol; ΔH°f[CO2(g)] = –393.5 kJ/mol; 

    ΔH°f[H2O(l)] = –285.8 kJ/mol.

    (A) 52 kJ/mol

    (B) 87 kJ/mol

    (C) 731 kJ/mol

    (D) 1.41 x 103 kJ/mol

    (E) 2.77 x 103 kJ/mol

    76706

    (A) 52 kJ/mol.

    (A) 52 kJ/mol.

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