Name __________________________________________________ Date ______________________________

Lesson 6 Identifying Chemical Reactions ReviewMain Ideas

Read each item. Then select the letter next to the best answer.

1. Investigators at a crime scene will often use a substance known as luminol to detect trace amounts of blood.When a luminol mixture is sprayed onto a surface, any blood that is present on the surface will start glowingblue!

Which of the following best describes the blue glow?

A. It is a physical property of luminol.B. It is a product of the reaction between luminol and blood.C. It is a sign that a reaction occurred between luminol and blood.D. It is a condition for a reaction to occur between luminol and blood.

2. A student is visiting his grandmother’s house and notices that she has lactose-free milk in her refrigerator. Hedoes some research on lactose-free milk and finds out that it is just milk that contains the lactase enzyme. Hehypothesizes that the lactase causes the milk to undergo a chemical reaction in order to make it lactose-free.

Which of the following observations best supports the student’s hypothesis?

A. The lactose-free milk smells about the same as regular milk.B. The lactose-free milk has a different taste from regular milk.C. The lactose-free milk appears to be the same color as regular milk.D. The lactose-free milk has a shorter expiration date than regular milk.

3. For a class experiment, a student needs to separate a mixture of salt crystals, sulfur powder, and iron filings.To do this, she first runs a magnet over the mixture to extract the iron. She then adds water to the remainingmixture to dissolve the salt, after which she filters out the sulfur. She finally boils off the water to leave behindsalt crystals.

At which point during this procedure did a chemical reaction occur?

A. after removing the iron, because this caused the salt and sulfur to mixB. after dissolving the salt in water, because this caused them to combineC. after boiling the saltwater, because heat was added to start the reactionD. No chemical reaction occurred because no new products were formed.

4. Magnesium metal burns white when used in fireworks. It can react with oxygen gas and nitrogen gas in theair to produce magnesium oxide and magnesium nitride respectively. A fireworks engineer wants todetermine which substance is the major product, and so she collects multiple samples of the powderedproduct that is left behind after a magnesium firework explosion. She records the volume and mass of eachsample in the data table provided below. Also provided below are the densities of each substance involved inthis reaction.

Based on the provided data tables, what is the major product when magnesium reacts with oxygen gas andnitrogen gas in the air?

A. magnesiumB. magnesium oxideC. magnesium nitrideD. oxygen and nitrogen

5. Antibiotics are a class of medications that are used for fighting bacterial infections. They react with importantstructures in a bacteria cell, which ultimately causes the bacteria to die off. Doctors often prescribe broad-spectrum antibiotics, which work against most if not all bacteria. Three of the most common antibiotics arepenicillin, streptomycin, and neomycin. Provided below is a graph showing the effectiveness of each of theseantibiotics against different types of bacterial infections.

Based on the provided graph, which antibiotic is the most effective in treating bacterial infections?

A. penicillin, because it is highly effective against six of the listed bacteriaB. neomycin, because it is the most effective against most of the listed bacteriaC. streptomycin, because it is slightly effective against all of the listed bacteriaD. All three antibiotics are equally effective against all of the listed bacteria.

6. Atorvastatin is one of the most important medications in the United States. It reacts with a liver enzyme tocause a decrease in cholesterol levels. Provided below is a graph showing how different daily doses ofatorvastatin affects cholesterol levels over several weeks.

Which of the following conclusions can be made based on the provided graph?

A. 80 mg of atorvastatin lowered cholesterol levels the least.B. 2.5 mg of atorvastatin lowered cholesterol levels the most.C. The biggest change in cholesterol levels occurred between weeks 2 to 6 of any dose.D. The biggest change in cholesterol levels occurred after the first 2 weeks of any dose.

Investigation A

A scientist recently discovered an unknown compound during one of her experiments. To study the unknowncompound, she used a technique known as “combustion analysis” to determine the amount of carbon andhydrogen in the sample. Provided below is a diagram showing how a combustion analysis device operates.

7. Based on the provided diagram, which of the following substances will initially react with the unknowncompound?A. oxygen gas, O2

B. sodium hydroxide, NaOHC. magnesium perchlorate, Mg(ClO4)2

D. carbon dioxide gas and water, CO2 and H2O

8. Based on the provided diagram, which of the following conditions is used to initiate the reaction?A. mixingB. heatingC. coolingD. The reaction will spontaneously begin on its own.

9. The scientist noticed that at the end of the combustion analysis, a colorless and odorless gas was coming outof the device. However, she does not know if that gas is just oxygen gas or a mixture of oxygen andadditional gases (that may contain other elements). What could she do to determine if the gas coming out ofthe device is just oxygen gas or a mixture of gases?A. Compare the odor of the gas with pure oxygen gas.B. Rerun the gas through the device to isolate pure oxygen gas.C. Compare the visual appearance of the gas with pure oxygen gas.D. Test the flammability of the gas in comparison with pure oxygen gas.

Investigation B

A group of students are investigating how magnesium metal (Mg) reacts with hydrochloric acid (HCl). Undertheir science teacher’s supervision, they mix magnesium metal with hydrochloric acid in a flask. Themagnesium disintegrates over the course of the reaction, and the students collect the resulting gas in aballoon as shown in the picture below.

Their teacher challenges them to design a reaction that will maximize the amount of gas produced in thisreaction. The students have a limited supply of 0.5-gram pieces of magnesium, but they are allowed to useas much hydrochloric acid as they want. They modify and repeat their experiment multiple times, and recordthe data for each trial in the table shown below.

10. Based on the provided data, which of the following amounts of magnesium and hydrochloric acid is most likelyto produce between 100 and 300 mL of gas?A. 1.0 g Mg and 90 mL HClB. 0.5 g Mg and 90 mL HClC. 0.5 g Mg and 30 mL HClD. 0.5 g Mg and 10 mL HCl

11. One of the students claims that continuing to use more hydrochloric acid (while keeping the amount ofmagnesium constant at 0.5 g) will increase the volume of gas produced. Based on the provided data, is thisclaim true or false?A. True, the amount of gas produced keeps increasing after 50 mL of acid is used.B. False, the amount of gas produced stops increasing after 50 mL of acid is used.C. True, the amount of gas produced keeps increasing after 100 mL of acid is used.D. False, the amount of gas produced stops increasing after 100 mL of acid is used.

12. Another student claims that in order to increase the volume of gas produced, they should test other types ofacid like nitric acid or sulfuric acid.A. use the same amounts of magnesium and acid, but change the type of acidB. use the same amount of magnesium, but change the amount and type of acidC. use the same amount of acid, but change the amount of magnesium and type of acidD. change the amounts of magnesium and acid, and change the volume of acid

Expressing Science Practices, Concepts, and Ideas

Read the directions for each item carefully and use the space provided to respond.

13. You work for a medical drug company that has decided to open up a new chemical plant nearby the town ofChemton. Because it takes considerable manpower to run a plant, your company would like to hire peoplefrom Chemton. However, the residents all seem to be a little wary of the plant, possibly even afraid!

In order to reassure the townspeople that the chemical plant will be safe and beneficial to them, you havebeen asked by the Public Relations department to write up a short presentation to inform the public aboutchemical reactions. Your two-paragraph presentation should explain:• WHAT A CHEMICAL REACTION IS, AND WHAT GENERALLY OCCURS IN A CHEMICAL REACTION• WHAT CONDITIONS CAN CAUSE A REACTION, AND WHAT TYPES OF EVIDENCE CAN BE USED TODETERMINE IF A REACTION HAS OCCURRED• HOW REACTIONS ARE INVOLVED IN CREATING AND EVALUATING NEW MEDICINES*INCLUDE AT LEAST 4 WORDS FROM THE WORD BANK

WORD BANK: Chemical Reaction; Clinical Trial; Product; Property; Reactant; Scientific Evidence

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