Activity b (continued from previous page)
vec reset set the water temperature to 100 cand the
vater temperature to 100c and the ice volume to 50 cm
play how does the situation compare to the previous one
dose a theory: based on what you have observed, explain why you think phase changes
ecur it possible discuss your theory with your classmates and teacher.
apply use your theory to explain what happens at the molecular level in each of the
following situations. also, list the temperature at which each transition occurs.
a
lce is warmed to the melting point.
temperature:
b. water is warmed to the boiling point.
temperature:
c water is cooled to the freezing point.
temperature:
8. extend your thinking: click reset. set the water temperature to 0 °c, the ice volume to
o cm. and add/remove heat energy to -400 j/s. click play and wait until all of the water
freezes
a. what volume of ice is created from 200 cm
of water?
b. why do water pipes sometimes burst in the winter? gizmo phase changes

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.

One of the hopes for solving the world's energy problem is to make use of the fusion reaction 21h +31h --> 42he + 10n + energy how much energy is released when 1 mol of deuterium is fused with 1 mol of tritium according to the above reaction? the masses of the atoms and the neutrons are as follows: 21h = 2.0140 amu 31h = 3.01605 amu 42he = 4.002603 amu 10n = 1.008665 amu. the speed of light is 2.9979 x 108 m/s.

Heat energy, carbon dioxide, and water are released through which process? a. photosynthesis b. depolymerization c. digestion d. cellular respiration