ACT Science : How to find data representation in chemistry

Study concepts, example questions & explanations for ACT Science

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Example Question #61 : How To Find Data Representation In Chemistry

Current high levels of fossil fuel use, including coal-burning power plants and gasoline-powered automobiles, have helped contribute to the high concentrations of sulfur trioxide, SO3, found in the atmosphere. When sulfur trioxide and water interact, they can undergo the following chemical reaction to produce sulfuric acid, which is the main contributor to acid rain worldwide: 

 

Acid rain showers are particularly common near coal-burning power plants and large cities. These showers are responsible for significant economic damage to sidewalks, roads, and buildings. Scientists interested in studying the effects of acid rain often use basic substances like calcium carbonate, the main component of limestone buildings, and expose them to varying volumes of acid rain to determine what volume of acid rain is necessary to begin to erode a building. A sample graph of one scientist’s experiment is replicated below:

 Passage_ii_-_main_passage

Measuring acid and base levels is commonly done with a scale called pH, which uses the concentration of hydrogen ions to determine the acidity. Hydrogen ions are in a balance with hydroxide ions to give a scale with a range from 0 to 14. Values equal to or between 0 and 6.9 represent the acidic range where hydrogen ions predominate and values equal to or ranging from 7.1 and 14 represent the basic range where hydroxide ions predominate. Thus, the more hydrogen ions present, the more acidic the solution.

Scientists can tell when a titration (pH) experiment passes a certain pH using compounds called indicators. Indicators are usually colorless at pH levels below that of their specified color change. A table of indicators used by the above scientists and the pH at which they change colors is presented below. 

Passage_ii_table

What is the pH of a solution containing calcium carbonate and sulfuric acid when 15 mL of sulfuric acid have been added?

Possible Answers:

10

5

Correct answer:

10

Explanation:

This question asks us to use the provided figure to estimate the pH of a solution given an amount of acid added. Using the curve, we can see that a 15 mL addition of sulfuric acid corresponds to a pH of roughly 10. While we not be able to determine the exact number, we can use process of elimination with the answer choices to see which of the options presented is close to the number represented on the figure.

Example Question #61 : Chemistry

The Ideal Gas Law is as follows:

 is pressure as measured in Pascals,  is volume as measured in cubic meters,  is the number of moles of the gas,  is the gas constant known as 8.314 Joules per mole times Kelvin, and  is the temperature measured in Kelvin.

A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.

 

Volume of the container

Pressure Measured in Pascals

1 cubic meter

49,884 Pascals

2 cubic meters

24,942 Pascals

3 cubic meters

16,628 Pascals

4 cubic meters

12,471 Pascals

5 cubic meters

 9,976.8 Pascals

6 cubic meters

 8,314 Pascals

7 cubic meters

 7,126.2 Pascals

TABLE 1 

 

And they graph their findings in Figure 1.

Img021

FIGURE 1

 

Will the pressure of a gas ever be ?

Possible Answers:

Yes. If the number of moles is 0 or if the temperature would ever reach 0 Kelvin.   

Yes, but only if the volume is 0 cubic meters.

Yes, when the volume of a gas is less than 0.5 cubic meters.

No, because nothing is divisible by 0.

No, because R will never be 0.

Correct answer:

Yes. If the number of moles is 0 or if the temperature would ever reach 0 Kelvin.   

Explanation:

The only way a gas can have a pressure of  is if there is no gas (0 moles) or if the temperature is 0 Kelvin. 0 Kelvin is absolute 0 and would mean that all movement of molecules has stopped and there is no pressure. Volume cannot be 0. If volume is 0, the equation cannot be solved because nothing is divisible by 0.

Example Question #63 : How To Find Data Representation In Chemistry

The Ideal Gas Law is as follows:

               

 is pressure as measured in Pascals,  is volume as measured in cubic meters,  is the number of moles of the gas,  is the gas constant known as 8.314 Joules per mole times Kelvin, and  is the temperature measured in Kelvin.

A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.

 

Volume of the container

Pressure Measured in Pascals

1 cubic meter

49,884 Pascals

2 cubic meters

24,942 Pascals

3 cubic meters

16,628 Pascals

4 cubic meters

12,471 Pascals

5 cubic meters

 9,976.8 Pascals

6 cubic meters

 8,314 Pascals

7 cubic meters

 7,126.2 Pascals

TABLE 1 

 

And they graph their findings in Figure 1.

Img021

FIGURE 1

Will the graph ever cross the y-axis (the axis on which pressure is measured)?

Possible Answers:

Yes, when the controlled variable of the number of moles is changed to 40.

Yes, when volume is 0 cubic meters.

No, because in order for it to do that, Volume would have to be 0. Volume will never be 0 because an equation cannot be solved if it requires being divided by 0.

Yes, but it will cross at less than .

No, it would only cross the y-axis if the volume was infinite, and it is not possible to create a container with an inifinite number of cubic meters.

Correct answer:

No, because in order for it to do that, Volume would have to be 0. Volume will never be 0 because an equation cannot be solved if it requires being divided by 0.

Explanation:

The lower the volume, the closer to the  y-axis the graph will get, but it can never reach 0.  If volume is measured at 0, the equation would have to be divided by 0.  An equation cannot be divided by 0.  

Example Question #64 : How To Find Data Representation In Chemistry

The Ideal Gas Law is as follows:

               

 is pressure as measured in Pascals,  is volume as measured in cubic meters,  is the number of moles of the gas,  is the gas constant known as 8.314 Joules per mole times Kelvin, and  is the temperature measured in Kelvin.

A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.

 

Volume of the container

Pressure Measured in Pascals

1 cubic meter

49,884 Pascals

2 cubic meters

24,942 Pascals

3 cubic meters

16,628 Pascals

4 cubic meters

12,471 Pascals

5 cubic meters

 9,976.8 Pascals

6 cubic meters

 8,314 Pascals

7 cubic meters

 7,126.2 Pascals

TABLE 1 

 

And they graph their findings in Figure 1.

Img021

FIGURE 1

What is the pressure at temperature 0 Kelvin?

Possible Answers:

The answer cannot be determined from the data available.

Correct answer:

Explanation:

The temperature and pressure are directly proportional to one another. If the temperature reaches 0 Kelvin (which is absolute 0, the temperature at which molecules no longer move at all), there will be  of pressure because anything multiplied by 0 is 0.

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