Read the descriptions below of two substances and an experiment on each. Decide whether the result of the experiment tells you the substance is a pure substance or a mixture, if you can. • Sample A is a solid yellow cube with a total mass of 50.0 g. The cube is ground to a fine orange powder and added to a 500 ml beaker full of water. The beaker is stirred vigorously. Some of orange powder settles to the bottom of the beaker, and some rises to the top and floats on the water. When the powder at both the bottom and the top of the beaker is filtered out, dried, and weighed, the total mass is measured to be 50.1 g. • Sample B is 100 mL of a clear liquid. The density of the liquid is measured, and turns out to be 0.77 g/mL. The liquid is then heated in a flask until it boils. The vapor that rises off the bolling liquid is collected for 10 minutes and cooled until it condenses into a separate beaker. The density of the liquid that remains in the flask is then measured, and turns out to be 1.04 g/mL. Opure substance х Is sample A made from a pure substance or a mixture? If the description of the substance and the outcome of the experiment isn't enough to decide, choose "can't decide." mixture O can't decide) O pure substance Is sample B made from a pure substance or a mixture? If the description of the substance and the outcome of the experiment isn't enough to decide, choose "can't decide mixture (can't decide)

Sodium sulfate dissolves as follows: na2so4(s) → 2na+(aq) + so42- (aq). how many moles of na2so4 are required to make 1.0 l of solution in which the na concentration is 0.10 m?

Show transcript transcripts online experiment: atomic structure [the history of atomic theory] this animation will you test rutherford’s hypothesis that it took a great number of shots to actually hit the nucleus because the size of the atom was so much larger than the nucleus.[clipboard and pencil with a diagram of rutherford’s gold foil experiment] we are going to use a cardboard box to represent the atom, a wooden block to represent the nucleus, and marbles to represent the alpha particles. [animated cardboard box, wooden block, and marbles] the box’s measurements are: length = 50 cm, width = 25 cm, and height = 25 cm. the measurements of the block are: length = 10 cm, width = 10 cm, and height is 5 cm. jose and priscilla will conduct the experiment. [animated boy and girl] priscilla put the block in the box on the floor. jose will close his eyes and drop marbles into the box trying to hit the block. priscilla will count the number of times the marbles hit the block and move the block in the box after each hit. [animated block moving inside the box. marble dropping into the box.] here is priscilla’s data of how many times the marble hit the block. out of 100 marble drops or shots, the marble hit the block 32 times. [data table: first column: marble, with rows 1 to 100; column 2: hit, with rows indicating yes or no. last row: total hits] now you can follow the directions in the experiment to present your findings. present your findings when you are finished with the experiment, complete the following data analysis and record your answers in the essay box below. determine the volume of the box and the block. determine the ratio of the block to the box: multiply this number by 100 to turn it into a percent. complete this statement: the volume of the block is percent of the volume of the box. determine the ratio of the number of hits to the number of shots: multiply this number by 100 to turn it into a percent. complete this statement: the block was hit percent of the time. compare the results of step 2 to the results of step 3. are the percentages similar? write a conclusion discussing the following items: based on your findings, do you think rutherford's hypothesis was reasonable? restate rutherford's hypothesis and describe how you tested it. state whether your results support the hypothesis. if they do not, can you suggest some error in experimental procedure (other than general human error) that might explain it? finally, explain how this experiment confirms the nuclear model of the atom and the idea that most of the atom is empty space.

The equation below shows a chemical reaction. a + b + heat —> c + d according to the law of conservation of energy, which statement is true? a. the reactants absorb heat because they have less energy than the products. b. the products release heat because they have more energy than the reactants. c. the reactants generate heat because they have more energy than the products. d. the products require heat to form because they have less energy than the reactants.