Chapter 1

How does a law differ from a theory?

Suppose you wanted to explore the role of sunlight on plant growth. Explain what you would do to go through one cycle of the scientific method, including a prediction you might make.

The scientific method is often considered foolproof and incapable of giving wrong answers, and yet history shows that scientists are sometimes wrong. What are some factors that cause the scientific method to give invalid results?

Which of the following are elemental substances and which are compounds: baking soda, \(\mathrm{NaHCO}_{3}\); graphite, \(\mathrm{C} ;\) dry ice, solid \(\mathrm{CO}_{2}\); metallic sodium, Na; metallic mercury, Hg?

Which of the following are elemental substances and which are compounds: diamond, a solid form of carbon, \(\mathrm{C}(s) ;\) liquid water, \(\mathrm{H}_{2} \mathrm{O}(l) ;\) nitric acid, \(\mathrm{HNO}_{3}(l)\); gaseous nitrogen, \(\mathrm{N}_{2}(g)\); liquid nitrogen, \(\mathrm{N}_{2}(l) ?\)

Classify each of the following as science or technology: (a) Trying to understand where the Sun gets its energy (b) The search for anticancer drugs (c) The invention of the transistor (d) The discovery of the electron (e) Sending a person to the Moon

Which one of the following is a compound: ozone, \(\mathrm{O}_{3}\); stainless steel, a combination of iron and other metals; sulfuric acid, \(\mathrm{H}_{2} \mathrm{SO}_{4} ;\) brewed coffee.

Residential ozonators work by passing an electric current through the air, converting the oxygen in the air to ozone. Is this process a chemical reaction or a physical transformation of oxygen? Explain.

Classify each of the following as elemental substance, compound, or mixture: (a) Milk (b) Chocolate cake (c) Clean snow, \(\mathrm{H}_{2} \mathrm{O}(s)\) (d) The simple sugar fructose, \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) (e) The mercury, \(\mathrm{Hg}\), in a thermometer

What is the name of the process by which matter changes from the liquid state to the gas state?

Match each symbol with the correct element name: (a) Na (b) Fe (c) Co (d) Sn (e) \(\mathrm{Mn}\) Possible names: neon, fermium, copper, mercury, cobalt, scandium, magnesium, phosphorus, manganese, iron, sodium, potassium, argon, tin, silver, gold, calcium.

The development of rust spots on an automobile body is an example of a _____ change. (physical or chemical)

The concise generalization of the results of a number of experiments is known as scientific _________.(experiment, law, or theory)

Which of the following can form a homogeneous mixture when mixed thoroughly with water: table salt, sand, table sugar, gold?

What is the difference between a spoonful of sugar dissolved in a glass of water and a spoonful of sugar melted over a candle flame?

Give three examples of a homogeneous mixture of two liquids.

Give an example of a homogeneous mixture of a gas in a liquid.

Give an example of a gas dissolved in another gas. Is this mixture homogeneous?

When nitrogen dioxide gas is cooled, it changes from brown to colorless. Is this more likely a chemical change or a physical change?

Mixtures can always be separated by physical means. Describe how you would separate the components in a mixture of sand and iron filings.

Mixtures can always be separated by physical means. Describe how you would separate the components in a mixture of table salt and sand.

Can you think of a physical means of separating hydrogen from oxygen in a sample of pure water, \(\mathrm{H}_{2} \mathrm{O}\) ?

All the metals in the first column of the periodic table react with water because they all have a single electron in their outermost occupied electron shell. This statement is an example of a scientific _____ .(law or theory)

In the chemical reaction for the "burning" of sugar, \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}+6 \mathrm{O}_{2} \rightarrow 6 \mathrm{CO}_{2}+6 \mathrm{H}_{2} \mathrm{O}\), which substances are the reactants and which are the products? Does this equation represent a chemical change or a physical change?

Which one of the following is a homogeneous mixture: milk shake, 14 -karat gold (made by melting gold and other metals together), fog, blood?

Which one of the following is a heterogeneous mixture: fog, gasoline, aluminum-magnesium alloy (made by melting these metals together), mixture of \(\mathrm{N}_{2}(g)\) and \(\operatorname{Ar}(g)\) ?

True or false? The melting point and freezing point of water are the same temperature at normal atmospheric pressure.

Which one of the following is an elemental substance: water, \(\mathrm{H}_{2} \mathrm{O} ;\) bronze, made by melting copper and tin together; table salt, \(\mathrm{NaCl}\); ozone, \(\mathrm{O}_{3} ;\) sulfur dioxide, \(\mathrm{SO}_{2} ?\)

Which one of the following is a homogeneous mixture: orange juice with pulp, wood, fog, bronze (made by melting copper and tin together)?

True or false? A theory is an attempt to explain why a law is true.

Which one of the following is a compound: ozone, 18 -karat gold (made by melting gold and other metals together), \(\mathrm{NaCl}\), liquid nitrogen, iced tea?

Which is larger, a degree Celsius or a degree Fahrenheit, and by roughly how much is it larger? Justify your answer.

The freezing point of nitrogen is \(-210.0{ }^{\circ} \mathrm{C}\). The boiling point of nitrogen is \(-195.8^{\circ} \mathrm{C}\).