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Seokjin Kim

Seokjin K.

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What is the limiting reagent? How much of the other reactant is in excess?

What is the limiting reagent? How much of the other reactant is in excess?

Introductory Chemistry

Stoichiometry and the Mole

Limiting Reagents

A major source of air pollution years ago was the metals industry. One common process involved "roasting" metal sulfides in the air: $$ 2 \mathrm{PbS}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{PbO}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{g}) $$ If you heat 2.5 mol of $\mathrm{PbS}$ in the air, what amount of $\mathrm{O}_{2}$ is required for complete reaction? What amounts of $\mathrm{PbO}$ and $\mathrm{SO}_{2}$ are expected?

A major source of air pollution years ago was the metals industry. One common process involved "roasting" metal sulfides in the air: $$ 2 \mathrm{PbS}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{PbO}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{g}) $$ If you heat 2.5 mol of $\mathrm{PbS}$ in the air, what amount of $\mathrm{O}_{2}$ is required for complete reaction? What amounts of $\mathrm{PbO}$ and $\mathrm{SO}_{2}$ are expected?

Chemistry and Chemical Reactivity

Calculate the binding energy per nucleon of the ${ }_{15}^{31} \mathrm{P}$ nucleus.

Calculate the binding energy per nucleon of the ${ }_{15}^{31} \mathrm{P}$ nucleus.

Physics

A granite ball of radius 2.00 $\mathrm{m}$ and emissivity 0.450 is heated to $135^{\circ} \mathrm{C}$ . (a) Convert the given temperature to Kelvin. (b) What is the surface area of the ball? (c) If the ambient temperature is $25.0^{\circ} \mathrm{C},$ what net power does the ball radiate?

A granite ball of radius 2.00 $\mathrm{m}$ and emissivity 0.450 is heated to $135^{\circ} \mathrm{C}$ . (a) Convert the given temperature to Kelvin. (b) What is the surface area of the ball? (c) If the ambient temperature is $25.0^{\circ} \mathrm{C},$ what net power does the ball radiate?

College Physics

Questions asked

ANSWERED

Aishwarya Krishnakumar verified

Numerade educator

Pieces of dry ice (CO2(s)) are placed in a zip-lock bag. The system absorbs 140 J of heat, which causes the CO2(s) to sublime. As a result, the system performs 85 J of work. Calculate the change in internal energy of the system, ΔU.

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ANSWERED

Aishwarya Krishnakumar verified

Numerade educator

The first step in the production of nitric acid from ammonia involves the oxidation of NH3 according to the balanced reaction below: 4 NH3(g) + 5 O2 (g) → 4 NO(g) + 6 H2O(g) How much energy is evolved or absorbed as heat in the oxidation of 10.1 g of NH3 if ΔfHo[NH3(g) = -45.9 kJ.mol-1, ΔfHo[NO(g)] = 90.3 kJ.mol-1 and ΔfHo[H2O(g)] = -241.8 kJ.mol-1.

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ANSWERED

Aishwarya Krishnakumar verified

Numerade educator

Nitroglycerin, C3H5(NO3)3, is a powerful explosive that forms four different gases when detonated: 2 C3H5(NO3)3(ℓ) → 3 N2(g) + 6 CO2(g) + 5 H2O(g) ΔHo = -2842.1 kJ Calculate the standard enthaly of formation (in kJ.mol-1) of CO2 if ΔfHo[C3H5(NO3)3(ℓ)] = -364.0 kJ.mol-1 and ΔfHo[H2O(g)] = -241.8 kJ.mol-1. (Please round your answer off to 1 decimal figure.)

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ANSWERED

Aishwarya Krishnakumar verified

Numerade educator

Calculate the change in enthalpy for the following reaction, using the appropriate standard enthalpies of formation given below. - ΔfH°[FeCℓ3(s)] = -412 kJ mol-1 - ΔfH°[FeCℓ2(s)] = -360 kJ mol-1 -ΔfH°[HCℓ(aq)] = -167.1 kJ mol-1 - ΔfH°[HCℓ(g)] = -127 kJ mol-1 2 FeCℓ2(s) + 2 HCℓ(g) → 2 FeCℓ3(s) + H2(g)

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ANSWERED

Aishwarya Krishnakumar verified

Numerade educator

The enthalpy change for the formation of NO(g) from its elements, as indicated below, cannot be measured directly because the reaction is reactant favoured. 1/2 N2(g) + 1/ 2 O2(g) → NO(g) Use Hess's Law as well as the enthalpy changes for the reactions below, which was determined experimentally, to determine the enthalpy change (in kJ) of formation for NO(g). - N2(g) + 3 H2(g) → 2 NH3(g) ΔfHo = -91.1 kJ. mol-1 - 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g) ΔfHo = -906.2 kJ.mol-1 - H2(g) + 1/2 O2(g) → H2O(g) ΔfHo = -241.8 kJ.mol-1

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ANSWERED

Aishwarya Krishnakumar verified

Numerade educator

Use Hess’s Law to determine the heat of reaction for the process. 2 Fe(s) + 3/2 O2(g) → Fe2O3(s) i. 2Fe(s) + 6H2O(ℓ) → 2Fe(OH)3(s) + 3H2(g) | ΔH° = +321.8 kJ ii. H2(g) + ½O2(g) → H2O(ℓ) | ΔH° = -285.8 kJ iii. Fe2O3(s) + 3H2O(ℓ) → 2Fe(OH)3(s) | ΔH° = +288.6 kJ

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ANSWERED

Aishwarya Krishnakumar verified

Numerade educator

Magnesium pieces (0.317 g) react in dilute acidic solution (137 mL) as follows: Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) The temperature of the solution increases from 22.2 °C to 44.8 °C. Determine the enthalpy change for the reaction in kJ per mol Mg(s) that reacts. (Assume that the specific heat capacity of the solution, and density of HCl(aq) can be approximated by the values for pure water. Furthermore, no heat energy is exchanged with the calorimeter).

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ANSWERED

Supreeta N verified

Numerade educator

What is the resulting temperature when 20 g of water at 92°C is mixed with 31 g of water at 18°C?

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ANSWERED

Supreeta N verified

Numerade educator

When 12.8 g NaOH dissolves in 222 g of water in a coffee-cup calorimeter, ΔH = −42.6 kJ/mol. The temperature increases from 19.6 °C to X °C. What is the value of X? (Assume that the solution has the same specific heat as liquid water, i.e., 4.18 J/g°C)

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ANSWERED

Supreeta N verified

Numerade educator

If 180.8 J are required to change the temperature of 18.58 g of a substance from 21.1 °C to 30.3 °C, what is the specific heat capacity of the substance?

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