Scientific Method
What is the first step in the scientific method?
What is making an observation?
What is the formula for density?
What is mass divided by volume?
What is the smallest unit of an element?
What is an atom?
What type of mixture is salad: homogeneous or heterogeneous?
What is heterogeneous?
Is melting ice a physical or chemical change?
What is physical?
What is a hypothesis?
What is a testable prediction or educated guess?
A block has a mass of 50 g and a volume of 10 cm³. What is its density?
What is 5 g/cm³?
What is the difference between an element and a compound?
What is an element is made of one type of atom, while a compound is made of two or more elements chemically bonded?
What method would you use to separate sand from salt water?
What is filtration?
What is a chemical property of iron (think of old cars)?
What is it reacts with oxygen to form rust?
What is the purpose of a controlling variables in an experiment?
What is to ensure the only thing affecting the dependent variable is the one single independent variable?
(Independent variable must respond to the dependent, changing multiple variables does not ensure that the outcome is due to the one variable purposely changed)
Which state of matter has a definite volume but no definite shape?
What is a liquid?
Is H₂O a molecule, a compound, or both? Explain your reasoning.
What is both?
Molecule - 2 or more atoms chemically bonded together.
Compound - 2 or more different atoms chemically bonded together.
How does a solution differ from a heterogeneous mixture?
What is a solution has particles dissolved at the molecular level, while a heterogeneous mixture has larger particles that may settle over time?
Which of the following is a chemical change: boiling water, burning wood, or dissolving sugar?
What is burning wood?
In an experiment testing how sugar affects rat growth, what is the independent variable?
What is the type of diet (sugar water vs. milk)?
A student measures the mass and volume of three substances. Substance A has a density of 1.2 g/cm³, B has 0.8 g/cm³, and C has 2.0 g/cm³. Rank them in order from least to most likely to float in water.
What is C (least likely), A, B (most likely)?
Which of the following is a pure substance: salt water, oxygen gas, or soil?
What is oxygen gas?
How does distillation separate components of a mixture?
What is by boiling and condensing substances based on their different boiling points?
Explain why dissolving salt in water is a physical change, even though the salt seems to disappear.
What is because no new substance is formed and the process is reversible?
Name two ways to improve the reliability of an experiment.
What are repeating trials and using larger sample sizes?
A liquid turns into a gas. Name this phase change, state whether it is endothermic or exothermic, explain your reasoning using kinetic energy and entropy.
What is evaporation?
What is endothermic? What is because the kinetic energy of the particles and the entropy of the particles increases as the particles have more movement and disorder, meaning they must have absorbed energy?
Explain why NaCl is considered a compound and not a molecule.
What is because NaCl is formed by ionic bonds, not covalent bonds, so it doesn’t form discrete molecules? It forms a solution.
A mixture contains iron filings, salt, and sand. Describe a step-by-step method to separate all three.
hat is use a magnet to remove iron, dissolve salt in water and filter out sand, then evaporate water to recover salt?
A student mixes two clear liquids and observes bubbling and a temperature increase. What type of change occurred and how do you know?
What is a chemical change, because gas was produced and heat was released, indicating a new substance formed?