What is the ratio of atoms of hydrogen to atoms of oxygen, H:O, in ammonium sulf

Question

What is the ratio of atoms of hydrogen to atoms of oxygen, H:O, in ammonium sulfate, (NH_4)_2SO_4? (a) 1:1 (b) 8:1 (c) 3:2 (d) 2:1 (e) 4:1 2. The number of significant figures in the number 0.01020 is (a) 2 (b) 4 (c) 5 (d) 3 (e) 6 3. The enthalpy change is -400 kJ for the reaction: 2 Aj(s) + 3/2 O_2j(g) rightarrow AI_2O_3(s). What is the DetlaH for the following reaction? 2 AI_2O_2(s) rightarrow 4 AI(s) + 3 O_2(g) is: (a) -800 kJ (b) -400 kJ (c) 800 kJ (d) 400 kJ (e) 200 kJ 4. What volume of 0.250 M HCI is required to titrate 25.0mI of 0.050 M NaOH? (a) 5.0 mI (b) 50.0 mI (c) 250 mI (d) 25.0 mI (e) 12.5 mI 5. When 0.25 moles of carbon monoxide reacts with oxygen to give carbon dioxide, 142 kJ of heat are given off (liberated). DeltaHdegree for the following reaction is: CO(g) + 1/2 O_2(g) rightarrow CO_2(g) (a) -1136 kJ (b) -142 kJ (c) 568 kJ (d) 142 kJ (a) -568 kJ 6. A 50.0 g sample of H_2O(I) at 22.0 degreeC in an insulated container absorbs 2.09 kJ of heat. What is the final temperature of the water? Specific heat of H_2O(I) = 4.18 J/gdegreeC. (a) 22.5 degreeC (b) 10.0 degreeC (c) 25.0 degreeC (d) 41.8 degreeC (e) 32.0 degreeC 7. A value of 13.6 g/mI is equal to how many kg/liter? (a) 0.136 (b) 1.36 times 10^-2 (c) 1.36 times 10^1 (d) 1.36 times 10^4 (a) none of the above 8. In a spectroscopic experiment, the following wavelengths of radiation were identified. Which one has the lowest frequency? (a) 500 nm (b) 800 nm (C) 1200 nm (d) 210 nm (e) 650 nm

Explanation / Answer

When the reaction is reversed,Al2O3- 2Al+3/2O2, enthalpy change= 400 Kj When the reaction is multiplied with 2, we get 4Al2O3- 4Al +3O2 and enthalpy change = 800 Kj ( C is correct)

4. The reaction between HCl and NaOH is NaOH+HCl-> NaCl +H2O

Moles of NaOH= moles of HCl

Moles = molarity* Volume

M1V1= M2V

V1= 0.05*25/0.25=5ml ( A is correct)

5. 0.25 moles of CO gives 142 Kj that is deltaH= -142KJ

1 mole gives 142*4=-566 Kj ofheat ( E is correct)

6. Heat absorbed= mass*specific heat* temperature difference
2.09*1000= 50*4.18*(t-22) where t is the final temperature

t=32 deg.c ( e is the correct answer)

7. 13.6 g/ cc =13.6*10-3 Kg/cc = 13.6*10-3 kg/ 10-3 L=13.6 Kg/L ( C is correct)

8. Frequency is inversely related to wave length. So the wave length that is higher will have low frequency. In the present case, it is 1200 nm ( C is correct)

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