Introduction to Chemistry

A chemist is analyzing a sample of river water and observes that it contains various undissolved particles. Based on this observation, how would the chemist classify this sample of river water?

When iron rusts, it combines with oxygen in the air to form iron oxide. Which type of change is this process?

A scientist measures the density and flammability of a newly synthesized substance. Which of the following correctly classifies these properties?

Consider a sealed container filled with water. When the container is heated, the water boils and turns into steam. What type of change has occurred, and what remains constant during this change?

In a chemical reaction, 10 grams of reactant A and 15 grams of reactant B are completely converted into product C. According to the basic principles of chemistry, what should be the mass of product C?

A researcher is studying a sample that contains carbon, hydrogen, and oxygen. The sample burns easily and is found in living organisms. Which branch of chemistry is most likely involved in this research?

Which of the following statements correctly describes the difference between an element and a compound?

Classify the following properties as either intensive or extensive: mass, volume, density, and temperature.

Consider the balanced equation: $2H_2(g) + O_2(g) \rightarrow 2H_2O(g)$. If 4 moles of $H_2$ react completely, how many moles of $H_2O$ are produced?

In the reaction $A + B \rightarrow C$, substance A is found to be the limiting reactant. What does this indicate about the reaction?

A student performs a reaction and calculates the theoretical yield of a product to be 25.0 grams. After performing the experiment, the student isolates 20.0 grams of the product. What is the percent yield of the reaction?

Which of the following statements correctly describes the behavior of acids and bases?

In the following reaction, identify which species is being oxidized: $Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s)$

Which type of chemical bond is characterized by the sharing of electrons within a 'sea' of electrons?

A solution is prepared by dissolving 10.0 grams of NaCl in 250 mL of water. If the molar mass of NaCl is 58.44 g/mol, what is the molarity of the solution?

Consider the equilibrium reaction: $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$. If the equilibrium constant (K) is 0.25, what does this indicate about the reaction at equilibrium?

For an exothermic reaction, which of the following statements is true regarding the change in enthalpy (ΔH)?

Which factor does NOT affect the rate of a chemical reaction?

A certain radioactive isotope has a half-life of 10 years. If you start with a 100 gram sample, how much of the isotope will remain after 30 years?

According to Le Chatelier's principle, what happens to the equilibrium of an endothermic reaction when the temperature is increased?

Which type of nuclear reaction is used in nuclear power plants to generate electricity?

Which of the following is an example of a strong acid?

What is the role of a catalyst in a chemical reaction?