Science Exam - Chemical Reactions Flashcards
Q: What is the difference between a chemical and a physical change?
A: A chemical change creates a new substance, while a physical change alters appearance without changing composition.
Q: Name three signs of a chemical reaction.
A: Colour change, gas production, formation of a precipitate, Smell, Heat, Light.
Q: What is the Law of Conservation of Mass?
A: Mass can not be created nor destroyed, only changed.
Q: Define acid and base.
A: An acid donates protons (H+ ions), while a base accepts protons in a reaction.
Q: What is a neutralisation reaction?
A: A reaction where an acid and base react to form water and a salt.
Q: What does the pH scale measure?
A: The acidity or basicity of a solution; 0-6 is acidic, 7 is neutral, and 8-14 is basic.
Q: What is a precipitation reaction?
A: A reaction where two solutions react to form an insoluble solid (precipitate).
Q: Define combustion reaction.
A: A reaction where a substance reacts with oxygen, often producing heat and light.
Q: Name four ways to increase the rate of a reaction.
A: Increasing temperature, surface area, concentration, and adding a catalyst.
Q: What is radioactivity?
A: The spontaneous emission of radiation by unstable atomic nuclei.
Q: Describe the types of radiation: alpha, beta, and gamma.
A: Alpha particles are heavy, beta particles are lighter electrons, and gamma rays are high-energy waves.
Q: What is an isotope?
A: Atoms of the same element with different numbers of neutrons.
Q: Explain how to balance a chemical equation.
A: Adjust the coefficients to ensure the same number of each atom on both sides of the equation.