Missed questions Flashcards
1
Q
What can be the definition for the rate of a reaction?
A
How many moles of the reactant was used up per second
2
Q
What are ways in which we can measure the rate of a reaction?
A
- Change in Concentration:
- Titration: Regularly sample the reaction mixture and titrate to determine the concentration of a reactant or product.
- Spectrophotometry: Measure the absorbance of light by a reactant or product at a specific wavelength. The change in absorbance over time correlates with the concentration.
- Change in Mass:
- Mass Loss: Measure the mass of the reaction mixture over time, especially if a gas is produced and escapes, reducing the mass.
- Change in Volume:
- Gas Volume: If the reaction produces a gas, measure the volume of gas evolved over time using a gas syringe or an inverted measuring cylinder over water.
- Change in Pressure:
- Manometry: Monitor the change in pressure in a closed system when a reaction produces or consumes a gas.
- Change in pH:
- pH Meter: Measure the change in pH if the reaction involves the production or consumption of hydrogen ions (H⁺). The rate of pH change indicates the reaction rate.
- Change in Electrical Conductivity:
- Conductometry: Monitor the change in electrical conductivity if the reaction involves ions. As the concentration of ions changes, so does the conductivity.
- Change in Color:
- Colorimetry: Measure the change in color intensity of the solution if the reaction involves colored substances. The intensity is related to the concentration of the colored species.
- Change in Temperature:
- Calorimetry: If the reaction is exothermic or endothermic, measure the temperature change over time. The rate of temperature change can be related to the reaction rate.
- Change in Pressure Drop in a Flow System:
- For reactions occurring in a flowing medium, monitoring the pressure drop across a catalyst bed can give an indication of reaction rate.
- Quenching:
- For fast reactions, samples are taken at different times and then quickly quenched (stopped) by rapid cooling or adding a reagent to stop the reaction. The concentration of reactants/products is then measured.
3
Q
For a zinc and sulfuric acid reaction. What cannot increase the rate of this reaction?
A
Increasing the pressure
4
Q
As temperature increases what also increases?
A
The collision rate and strength between all particles.
5
Q
A
6
Q
The flame test is used for determining
A
The identity of a metal
7
Q
What do open systems do?
A
Exchange energy and matter with the surroundings
8
Q
What is a bond energy?
A
amount of energy required to break 1 mole of a bond into its constituent gase
9
Q
What is the chemical equasion for an incomplete combustion
A
Fuel+ oxygen- CO+ water
