Answer:
When a gas is heated, the molecules move faster, bump into each other, and spread apart. Because the molecules are spread apart, they take up more space. They are less dense.
Answer:
B. adding heat to the system and having the system do work on the surroundings
Explanation:
The internal energy of a system is the energy contained within the system. From first law of thermodynamics we have the equation : dq=du+dw
and we know that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another therefore du is zero. dq = dw this means that the entire heat supplied is converted into work (on the surroundings)
However, some of the heat supplied is also used to increase the internal energy of the system
14. a. Acidic
15. b. Weaker
16. d. Dilute and weak
Explanation:
14. Which type of the solution is one with the pH of 3?
Solution with pH from 1 to 7 are acidic, equal to 7 is neutral and from 7 to 14 basic. The solution with the pH equal to 3 is <u>acidic</u>.
15. The smaller the value of the base dissociation constant (Kb), the <u>weaker</u> the base.
The dissociation reaction of a base (B) is:
B + H₂O → BH⁺ + OH⁻
Kb is defined as:
Kb = ( [BH⁺] × [OH⁻] ) / ( [B] × [H₂O] )
The potency of the base depends on the concentration of the hydroxide ion [OH⁻], so if the Kb ratio is small it means that the concentration of hydroxide ion is smaller so the base will be <u>weaker</u>.
16. A 0.39 M solution of an acid that ionizes only slightly in solution would be termed <u>dilute and weak</u>.
The acid is weak because is only slightly ionizing in solution. The therm diluted is a little bit arbitrarily because we ask yourself "diluted in respect with what"? I would characterize the acid to be diluted at a concentration of 1 M and concentrated at a concentration of 10 M.
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pH
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The nuclei of atoms become unstable when the repelling forces of the protons cannot be balanced by the number of neutrons in the nucleus. It then re-arranges itself randomly to a more stable configuration by emitting any of a series of particles. During radioactive decay, an atom does not collapse.
Since an atom is mostly empty space - that is it’s nucleus is relatively distant from the electron shells so, in the presence of extreme forces such as gravity inthe collapse of a large star, the inward pressures on the atom overcome the natural balance of the atomic structure and the ‘empty space’ disappears as nuclei are mashed together by the intense pressures and a neutron star is formed. Under even more external pressure, even the neutron star can collapse to form a black hole.
