In studying the effects of adding heat to different substances on each substance's temperature, a researcher conducted the following experiment. The researcher added 1,000 Joules of energy by a controlled heat lamp to four different substances. The temperature change in each substance that was caused by the heat was then measured and recorded. The results of this experiment are shown below.

The researcher is aware of a concept called specific heat and knows that lead has a lower specific heat than wood, which has a lower specific heat than cardboard, which has a lower specific heat than styrofoam. Therefore, the researcher has ordered the objects in the table from lowest specific heat (lead) to highest (styrofoam).

A new substance, Substance X, is discovered with a specific heat greater than that of cardboard but less than that of styrofoam. What would we expect would happen if we were to add 1,000 Joules of energy to a sample of Substance X assuming the exact same conditions as in the experiment above?

The rate of a reaction is defined as the rate at which the products of a reaction are produced. A researcher wants to investigate the rate of reaction of the combustion of theoretical compound . The researcher combusts different amounts of starting material (the theoretical compound and oxygen gas ) and measures how the rate of reaction is affected by changing the amounts of starting material. Because the researcher is concerned about how the conditions of his lab may change, the researcher repeats trial 1. The researcher finds that the results of repeating trial 1 were identical each time.

The results of the experiment are shown in the table below. The brackets ([]) indicate concentration measured in mol/L. 

According to the data in the table, what is the apparent relationship between the starting concentration of the theoretical compound and the rate of the reaction?

The rate of a reaction is defined as the rate at which the products of a reaction are produced. A researcher wants to investigate the rate of reaction of the combustion of theoretical compound . The researcher combusts different amounts of starting material (the theoretical compound and oxygen gas ) and measures how the rate of reaction is affected by changing the amounts of starting material. Because the researcher is concerned about how the conditions of his lab may change, the researcher repeats trial 1. The researcher finds that the results of repeating trial 1 were identical each time.

The results of the experiment are shown in the table below. The brackets ([]) indicate concentration measured in mol/L. 

According to the data, what is the apparent relationship between oxygen concentration and the rate of the reaction?

Gases can be described by their average molecular speeds. Gases are made up of huge numbers of molecules which vary greatly in speed. The average speeds of those molecules is related to the mass of the gas particles. For example, a heavy gas will have a much lower average molecular speed than a lighter gas. 

The rate of effusion of a gas is defined as the rate at which a gas in a chamber can escape through a pinhole. A gas molecule with a higher average molecular speed is more likely to exit a pinhole and therefore has a higher rate of effusion. 

The above diagram is a graph of the different speeds of the molecules of Gas Z and their different frequencies. Higher on the y-axis implies higher frequency while lower implies lower frequency. Which point most likely represents the average speed of Gas Z?

Gases can be described by their average molecular speeds. Gases are made up of huge numbers of molecules which vary greatly in speed. The average speeds of those molecules is related to the mass of the gas particles. For example, a heavy gas will have a much lower average molecular speed than a lighter gas. 

The rate of effusion of a gas is defined as the rate at which a gas in a chamber can escape through a pinhole. A gas molecule with a higher average molecular speed is more likely to exit a pinhole and therefore has a higher rate of effusion.

The above graph displays the speeds of the molecules of two gases (Gas A and Gas B) and their relative frequencies. Higher on the y-axis corresponds with higher frequency. If we know that Gas A or Gas B could either be hydrogen gas (weight = 1amu) or carbon dioxide (weight = 44amu) what could the identities of the gases be?

During digestion, the energy in food is converted to energy the body can use. Scientists use calorimetry experiments to measure the calories, or energy, provided by food when it is digested or burned. 

The relationship used to find the heat transferred energy  is given by , where  is the mass of the material,  is the given specific heat capacity, and  is the change in temperature of the material. 

In this experiment, food was burned over a Bunsen burner under a can of 200 ml of water. The temperature change of the water and mass change of the food can be used to determine the calories in four different food items.

Table 1 shows the values of the change of mass of the food items, the change in temperature of the water and the energy. Table 2 shows the energy to mass ratio of three of those food items.

                                                    Table 1

                                  Roasted Peanut  Peanut    Cracker    Cheese Puff

Water Temp. Initial         23.9 °C           33.2 °C     40.3 °C      53.9 °C

Water Temp. Final           30.0 °C           40.9 °C     55.9 °C      62.8 °C

Food Mass Initial             0.69 g             0.61 g       3.21 g        1.22 g

Food Mass Final               0.38 g             0.21 g       0.91 g        0.48 g

Energy                            1.22 Cal          1.54 Cal     3.12 Cal     1.78 Cal

                           Table 2

Sample         Energy to Mass Ratio (Cal/g)

     1                                 1.36

     2                                 3.93

     3                                 2.40

Based on the information in Tables 1 and 2, Sample 2 is most likely which of the following food items?

Nanoparticles are fabricated by vigorously mixing the constituent components of the particle in solution. A scientist has four different compositions that she has tested: Composition A, Composition B, Composition C, and Composition D. All of these compositions were observed under similar laboratory conditions using different mixing times. The average particle size for each scenario was recorded in the provided table. 

A component used in nanoparticle synthesis is polyethylene glycol, or PEG. It is known that larger concentrations of PEG create nanoparticles with smaller radii. Based on this information, which composition is most likely to contain the largest amount of PEG?

Nanoparticles are fabricated by vigorously mixing the constituent components of the particle in solution. A scientist has four different compositions that she has tested: Composition A, Composition B, Composition C, and Composition D. All of these compositions were observed under similar laboratory conditions using different mixing times. The average particle size for each scenario was recorded in the provided table. 

If the scientist requires nanoparticles larger than  for another experiment, then which two compositions should she use? 

Nanoparticles are fabricated by vigorously mixing the constituent components of the particle in solution. A scientist has four different compositions that she has tested: Composition A, Composition B, Composition C, and Composition D. All of these compositions were observed under similar laboratory conditions using different mixing times. The average particle size for each scenario was recorded in the provided table. 

The scientist wants to make the nanoparticles that are all the same size. If the minimum mixing time required to make nanoparticles is , then how can this be achieved? 

The Environmental Protection Agency compiled the following information about heavy metals in drinking water. Heavy metals are toxic, and thus must be monitored very closely. All amounts are given in parts per billion (ppb), a common measurement of concentration for trace contaminants. Figure 1 shows total heavy metal contamination in each city as a makeup of various percentages of specific contaminants. Figure 2 shows specific amounts of contaminants (with the same color coding) in ppb as well as total contamination level in ppb.

Figure 1

Figure 2

For each total amount of contamination in each city, which has the highest percent cadmium?