Paper 2

• Why is it important to measure the rate of reaction carefully?

  To ensure accurate results and comparisons
• What are the units for measuring volume and time in the rate of reaction?

  Centimeters cubed per minute
• How can you find the rate of reaction at a specific point on a graph?

  By drawing a tangent at that point and calculating its gradient
• What is the formula to calculate the gradient of a tangent?

  Change in vertical (y) divided by change in horizontal (x)
• What does a steep tangent indicate about the rate of reaction?

  It indicates a fast rate of reaction
• What is one method to follow a reaction involving a solid and gas?

  By measuring the loss of mass
• What happens to the mass when a gas is produced in a reaction?

  The mass decreases as the gas escapes
• How can gas production be measured in a reaction?

  Using a measuring syringe or an inverted measuring cylinder
• What is a visible change that can indicate a reaction is taking place?

  A color change from clear to opaque
• What is a specific reaction mentioned that requires careful handling?

  The reaction between sodium thiosulfate and hydrochloric acid
• Why is health and safety important in the mentioned reaction?

  To prevent irritation and exposure to harmful gases
• What should be consistent when measuring the rate of reaction in the color change experiment?

  The same person should measure the rate of reaction
• What is a potential error when collecting gas in a measuring cylinder?

  Gas already present in the measuring cylinder before starting
• How does temperature affect the rate of reaction?

  Higher temperatures increase the rate of reaction
• What happens to particles at higher temperatures?

  They move faster and collide more frequently
• What is the relationship between surface area and rate of reaction?

  Larger surface area leads to a faster rate of reaction
• Why do powdered substances react faster than lumps?

  Powdered substances have more surface area available to react
• How does pressure affect the rate of reaction?

  Higher pressure increases the rate of reaction
• What is the role of a catalyst in a reaction?

  A catalyst lowers the activation energy needed for a reaction
• What does the activation energy represent in a reaction?

  The energy barrier that must be overcome for a reaction to occur
• What does Le Chatelier's principle state?

  The reaction will shift to counteract any changes made to it
• What happens when the temperature of a reversible reaction is increased?

  The endothermic reaction will increase to compensate
• What is a hydrocarbon?

  A compound made up of hydrogen and carbon only
• What are alkanes?

  Hydrocarbons with single bonds only
• What is the general formula for alkanes?

  C$n$H$2n +$$2$
• What is the first alkane with one carbon atom?

  Methane
• What is the second alkane with two carbon atoms?

  Ethane
• What is the third alkane with three carbon atoms?

  Propane
• What is the fourth alkane with four carbon atoms?

  Butane
• What is fractional distillation used for?

  To separate different lengths of hydrocarbons from crude oil
• What happens to crude oil during fractional distillation?

  It is heated until it becomes a gas and then condensed
• What is produced at the bottom of the distillation column?

  Residue from long-chain hydrocarbons
• What type of hydrocarbons come off at the top of the distillation column?

  Short hydrocarbons
• Why are short hydrocarbons more useful than long ones?

  They are more flammable and have more applications
• What is the test for alkenes?

  Using bromine water, which turns from orange to colorless
• What does complete combustion of a hydrocarbon produce?

  Water and carbon dioxide
• What happens to a pure substance at its melting point?

  It melts at a specific temperature
• How does a mixture behave compared to a pure substance at melting points?

  A mixture melts over a range of melting points
• Why is it important to understand activation energy in reactions?

  It helps predict how easily a reaction can occur
• Why is accurate measurement of the rate of reaction significant?

  It ensures reliable and valid experimental results