Chemical Kinetics and Conversions Quiz

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Questions and Answers

What is the equation for concentration over time in a zero-order reaction?

C = kt + C0

C = C0 - kt (correct)

C = kC0 - t

C = C0 + kt

What characterizes first-order decay rates?

The rate of decay happens at a constant rate regardless of concentration.

The rate of decay is independent of concentration.

The rate of decay is directly proportional to the concentration present. (correct)

The rate of decay is proportional to the square of concentration.

What is the conversion factor for converting meters to feet?

1.8

10.7639

3.2808 (correct)

0.06243

Which prefix corresponds to the factor of $10^{-6}$?

micro Signup and view all the answers

In the differential equation form dC/dt = -k, what does 'k' represent?

The reaction rate constant. Signup and view all the answers

In SI units, what is the mass of 1 kilogram expressed in pounds?

2.2046 lb Signup and view all the answers

For a reaction undergoing generation, which order is most commonly encountered?

Zero-order Signup and view all the answers

What is the volume conversion factor from cubic meters to cubic feet?

35.3147 Signup and view all the answers

What happens to the concentration of a substance in a zero-order reaction over time?

Decreases linearly Signup and view all the answers

Which of the following temperatures convert to degrees Fahrenheit using the equation $1.8(°C) + 32$?

100 °C Signup and view all the answers

Which statement accurately describes the first-order reaction rate of radioactive decay?

Decay rate decreases as the concentration decreases. Signup and view all the answers

What is the equivalent density in pounds per cubic foot for 1 kg/m³?

0.06243 lb/ft³ Signup and view all the answers

In which form is the equation for first-order generation expressed?

r(C) = kC Signup and view all the answers

Which of the following best describes zero-order kinetics in relation to pollutants?

The reaction rate is constant regardless of pollutant concentration. Signup and view all the answers

Which volume unit is equivalent to 1 cubic meter in square feet?

35.3147 ft³ Signup and view all the answers

What is the prefix that represents $10^{-9}$?

nano Signup and view all the answers

What is the process called when heat added to a substance causes a change in temperature?

Sensible heating Signup and view all the answers

What is the formula to account for the latent heat stored in a substance during a phase change?

Energy = m L Signup and view all the answers

How much energy is required to change the temperature of 1 kg of ice by 1°C?

2.1 kJ Signup and view all the answers

What is the latent heat of vaporization for water at 100°C?

2,257 kJ Signup and view all the answers

What is the latent heat of fusion for water?

333 kJ Signup and view all the answers

Which temperature corresponds to the heat of vaporization listed in the content?

100°C Signup and view all the answers

How much energy is needed to completely melt 1 kg of ice?

333 kJ Signup and view all the answers

What specific heat is needed to raise the temperature of water?

4.18 kJ/°C Signup and view all the answers

What is the mass concentration of fluoride in water, given the calculation?

1.01 mg/L Signup and view all the answers

Using the formula $C = \frac{m}{V}$, what do 'm' and 'V' represent?

Mass of the substance and volume of the fluid Signup and view all the answers

How much water can be treated with the bag containing fluoride?

2.97 * 10^6 gallons Signup and view all the answers

What is the significance of the 'v' in ppmv?

It indicates the measurement is in volume only. Signup and view all the answers

What is the steady-state concentration found using the provided equation?

0.117 mg/m3 Signup and view all the answers

Which of the following factors affects the relationship between ppmv and mg/m3?

The molecular weight of the pollutant Signup and view all the answers

What will be the concentration of the pollutant in the lake one week after diverting the sewage outfall?

0.67 mg/L Signup and view all the answers

What does the ideal gas law equation, $PV = nRT$, primarily help to establish?

The relationship between mass and volume of a gas Signup and view all the answers

What is the method used for expressing pollutant concentrations in air pollution work?

Parts per million by volume Signup and view all the answers

What reaction-rate constant is assumed for the pollutants in the lake after the outfall diversion?

0.20/day Signup and view all the answers

What is the molar mass of fluoride used in the calculations?

19.0 g/mol Signup and view all the answers

How is the pollutant concentration calculated at a specific time after the outfall stops draining?

C(t) = Cq * (1 - exp(-kd * t)) Signup and view all the answers

Which parameter is NOT included when calculating the steady-state concentration?

Outflow rate (Qs) Signup and view all the answers

What is the effect of completely diverting the sewage outfall from the lake?

Sudden decrease in pollution concentration Signup and view all the answers

What is the volume of the lake analyzed in Example 9?

10,000,000 m3 Signup and view all the answers

What is the value of $t$ used for calculating the concentration at 6 P.M.?

1 hr Signup and view all the answers

What is the change in temperature of the river due to the energy released?

4.1°C Signup and view all the answers

What is the flow rate of the river mentioned in the calculations?

100.0 m3/s Signup and view all the answers

According to the second law of thermodynamics, what happens to some energy in heat engines?

It is always turned into waste heat. Signup and view all the answers

What is the role of the cold reservoir in the heat engine described?

It absorbs the waste heat from the engine. Signup and view all the answers

What does the Carnot engine diagram illustrate regarding heat energy?

Heat is transferred from a high-temperature to a low-temperature reservoir. Signup and view all the answers

In the context of thermodynamics, which of the following correctly describes the efficiency of heat engines?

They inherently produce waste heat during operation. Signup and view all the answers

What is the purpose of the steam system in a steam-electric plant?

To convert high-temperature heat into electrical power. Signup and view all the answers

What happens to energy that is not converted into useful work in a heat engine?

It is released as low-quality heat to the environment. Signup and view all the answers

Study Notes

Basic Units and Conversion Factors

Units most frequently used are milligrams (mg), micrograms (mcg), or moles (mol) per liter (L).
Table 1 provides a summary of units and conversion factors between SI (Système International) and USCS (United States Customary Systems) units.
- Includes conversions for length (meter to feet), mass (kilogram to pounds), temperature (Celsius to Fahrenheit), area, volume, energy, power, velocity, flow rate, and density.
Prefixes for various orders of magnitude are presented in Table 2.

Mass and Energy Transfer - Calculations

Fluoride mass calculation:
- To find the mass of fluoride in a 25 kg bag, the ratio of fluoride's molar mass is used (19.0 g/mol) to the molar mass of the material (42.0 g/mol).
- Result: 11.31 kg of fluoride.
Optimum fluoride concentration in water:
- Converting from molar concentration (mmol/L) to mass concentration (mg/L) using the appropriate conversion factors results in 1.01 mg/L.
Mass concentration formula:
- The general formula for mass concentration (C) is mass (m) divided by volume (V)

Pollutant Concentrations (Gaseous)

Pollutant concentration expression in terms of volume:
- Parts per million (ppm) is volume of pollutant per million volumes of the air mixture (1 ppmv)
The ideal gas law (PV=nRT) establishes relation between Volume and Mass concentration.
- P = absolute pressure (atm)
- V = volume (m³)
- n = moles of gas
- R = ideal gas constant = 0.082056 L-atm-K^-1-mol^-1
- T = absolute temperature (K)

Zero-order Kinetics

Zero-order reactions:
- The decay or generation rate is constant regardless of the changes in concentration level, which is independent of the substance's concentration.
- Concentration changes linearly with time.
The general equation: C = C₀ – kt, where C₀ is the initial concentration, and k is the reaction rate constant

First-order Kinetics

First-order reactions (decay and generation):
- The rate of reaction is directly proportional to the concentration of substance.
- Decay and generation rates may be any order, however zero-order is most common for generation and first-order for decay.
- The first-order reaction rate is r(C) =± kC, with k having units of reciprocal time (time⁻¹)

Steady-State Concentration (using Q, V, G, Ci, and kd symbols)

Calculating steady-state concentration:
- Example calculation using the formula C_q = (Q C_i + k_g V) / (Q +k_dV) for specific values of Q, V, G, C_i, and k_d .

Sudden Decrease in Pollutants

Example demonstrating the change in pollutant concentration due to a sudden interruption in the discharge of pollutants to a body of water.
Calculations for concentration after a week and the reaching a new steady-state condition of pollution.

Sensible Heating and Latent Heat

Sensible heating:
- Process where a substance changes temperature as heat is added.
Latent heat:
- Addition of heat that causes a phase change (e.g., melting, boiling)
Energy released or absorbed in phase change equation:
- Energy released/absorbed = m * L, with m is the mass and L is latent heat of fusion or vaporization.
Figure 13 illustrates the concepts of latent heat and specific heat for water, showing the various required energy when converting between ice, water, and steam.

Temperature Elevation of a River

Calculations for the elevation in temperature of a river with a specified amount of heat release rate using the equation:
- Rate of change in internal energy = m * c * ΔT.

Second Law of Thermodynamics (Heat Engine)

The second law of thermodynamics states that there will always be some waste heat in heat engine processes; it's impossible to convert heat completely to work.
Heat engine example (like a steam-electric plant): It takes heat from a high-temperature source, converts some into work, and rejects the remainder into a low-temperature reservoir.

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Description

Test your knowledge on chemical kinetics, including zero-order and first-order reactions, as well as important unit conversions. This quiz covers equations, decay rates, and more related to chemical reactions and measurement conversions. Perfect for students studying chemistry or related fields.