Unit 1 Chemical Reaction Practice Test

A student used a graduated cylinder in lab. What volume of liquid is found in the graduated cylinder? (DOK 1)

(hint: https://www.wisc-online.com/learn/natural-science/chemistry/gch302/measuring-volume-using-a-graduated-cylinder )

• 35mL

• 36mL

• 36.5mL

• 37mL

A particular type of medicine can be prescribed in 0.034 g or 0.025 g tablets. Why would a balance that measures to the hundredths place be dangerous to use in producing these tablets? (DOK 2)

• The hundredths place is the estimate so both types of tablets would round to 0.03 g and would be the same thing which would not help the patient.

• Our balances in class only go to the hundredths place.

• The danger is from not rounding to 0.03 g before you mass the medicine, due to the rules of significant figures

• Using a balance that can measure to the thousandths place would not be any safer

Two students measure and record the volume of the same sample of water in the graduated cylinder shown above. The first student recorded the volume as 16.0 mL, whereas the second student recorded the volume as 16 mL. The students decided that the two recorded measurements were equally valid. Which statement best identifies and explains the correct measurement? (DOK 2)

• a. The digits recorded in a measurement are related to the markings on the measuring tool. Markings indicate certain digits, whereas the final estimated digit corresponds to the space between the two smallest markings. Because this graduated cylinder has markings for every 1 mL, digits in the tens and the ones places are certain; the digit in the tenths place is estimated and must be recorded, making 16.0 mL the proper measurement.

• The final digit in a recorded measurement indicates the estimated digit, which corresponds to the space between two markings on the measuring tool. Since the final digit in the first measurement is a zero, it can be ignored, making the two measurements equal.

• Since the volume of 16.0 mL has the most digits, it is the most precise measurement, and therefore, must be the correct measurement. The more digits recorded, the more precise the measurement, and scientists strive to be as precise as possible when collecting data.

• Measurements should be simplified to make calculations using lab data clear and easy to use. The measurement of 16 mL is a simpler expression, and since the zero will not affect any calculations using these measurements, 16 mL must be the correct measure

How should you measure the mass of a white powder? (DOK 1)

• Place the powder on the balance and record the mass.

• Place the powder in a beaker and record the mass.

• Place the beaker on the balance. Add the powder. Record the mass.

• Place the beaker on the balance. Push tare or zero. Add the powder. Record the mass

Why is a graduated cylinder most appropriate for measuring the volume of a liquid instead of a beaker? (DOK 2)

• A graduated cylinder provides a more precise measurement to be made because the markings are closer together allowing more significant figures.

• A graduated cylinder estimates large volumes of liquid, whereas a beaker is used to transport large volumes of liquids.

• A graduated cylinder can hold acids and bases more safely because of the smaller opening.

• The meniscus is easier to see in a graduated cylinder and can be read easier than a beaker.

What are the coefficients for the following equation? (DOK 1)

___H₂ + __ O₂ --> ___H₂O

• 1,1,1

• 1,2,1

• 1,1,2

• 2,1,2

What are the coefficients for the following equation? (DOK 1)

__Mg + ___O2 --->___ MgO

• 1,1,1

• 1,1,2

• 2,1,2

• 1,2,1

What are the coefficients for the following equation? (DOK 1)

__CH₄ + ___O₂ ---> ___CO₂ + ___H₂O

• 1,4,1,2

• 1,3,1,4

• 1,5,4,2

• 1,2,1,2

There are other types of chemical reactions than the five types studied in this unit. One type is shown below. If we had to classify it as one of the five that we have learned, which type of reaction would this equation most likely be classified as and why? (DOK 2

• Single replacement because the element chlorine is replacing the element hydrogen

• Double replacement because the Cl and H are switching places in a double swap and two new compounds are formed

• Combustion because a hydrocarbon (CH₄) is involved and the chlorine is behaving like oxygen

• Synthesis because more complex substances are being made

A chemical equation is below.

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

What type of reaction is shown? (DOK 2)

• Decomposition because water and carbon dioxide are produced

• Decomposition because there are two products produced and oxygen is a reactant

• Combustion because water and carbon dioxide are produced and oxygen is a reactant

• Combustion because there are two products