1. A radioactive nucleus alpha decays to yield a sodium-24 nucleus in 14.8 hours
ID: 532565 • Letter: 1
Question
1. A radioactive nucleus alpha decays to yield a sodium-24 nucleus in 14.8 hours. What was the identity of the original nucleus? Show the nuclear equation that leads you to this answer.
2. Iron-59 has a half-life of 45.1 days. How old is an iron nail if the Fe-59 content is 25% that of a new sample of iron? Show all calculations leading to a solution.
3. Using at least 3 to 4 complete content related sentences, explain how the compressed gas in an aerosol can forces paint out of the can. Be sure to describe how the gas pressure inside the can changes as the paint is sprayed. Please refer to figure 14.5 in lesson 14.1.
4. pH is a measure of ______________.
a. hydrogen ion concentration. c. hydroxide ion concentration.
b. hydrogen gas concentration. d. hydrolysis.
5. A neutralization reaction between an acid and a base always produces
a. salt and acidic anhydride. c. water and basic anhydride.
b. salt and basic anhydride. d. salt and water.
6. If the pH of a solution is _____ the solution is basic.
a. 2 b. 5 c. 7 d. 10
25 – 30 Apply the appropriate word to the definition indicated. Not all words will be used.
25. _____
Heat content of a system at constant pressure
calorie (cal)
26. _____
Ability to do work
Chemical Potential Energy
27. _____
Disorder
Energy
28. _____
Energy of motion
Enthalpy
29. _____
Study of energy changes that ocrrue during chemic reaction and changes in states.
Entropy
30. _____
Amount of heat required to raise T of 1 g of pure water 1C
Joule
Kinetic energy
Heat (q)
Specific Heat
Thermochemistry
25. _____
Heat content of a system at constant pressure
calorie (cal)
26. _____
Ability to do work
Chemical Potential Energy
27. _____
Disorder
Energy
28. _____
Energy of motion
Enthalpy
29. _____
Study of energy changes that ocrrue during chemic reaction and changes in states.
Entropy
30. _____
Amount of heat required to raise T of 1 g of pure water 1C
Joule
Kinetic energy
Heat (q)
Specific Heat
Thermochemistry
Explanation / Answer
Iron-59 has a half-life of 45.1 days. How old is an iron nail if the Fe-59 content is 25% that of a new sample of iron? Show all calculations leading to a solution.
the relation between half life and rate constant is K=0.693/ half life= 0.693/45.1 =0.015366/day
the relation between iron % at any time is given by
Ct= Co*exp(-Kt), CO= initial concentration of iron, C= concentration at any time = CO*0.25,
hence C0*0.25= Co*e(-0.015366*t)
takin ln, ln(0.25)=-0.015366*t, t= 90 days= life of iron nail.
3.
Aerosol contains two components one that boils at low temperature and the other one boiling at high temperature. The high boiling component is meant for spraying, in this case the paint.
The compressed gas in the aerosl will have more enthalpy due to its presure. When pressure is released through the nozzle, the gas expands and lost enthalpy due to drop in pressure and from law of conservation of energy, the paint is pushed out at the expense of lost enthalpy of gas. as the paint gets sprayed, the gas can spreared through leading to more and more expnasion of gas.
4. pH= -log[H+]. hence pH is an indication of hydroxide concentration. ( A is correct)
5. A neutralization reaction between an acid and base gives rise to formation of salt and water. For example, The reaction between HCl (acid) and base (NaOH) gives rise to a salt.
NaOH+ HCl------>NaCl+ H2O
6. if pH is <7, the solution is acidic, pH=7, the solution is neutral and pH>7, the solution is basis. Hence in the present case, 10 is in the basic region.( D is correct)
7. heat conent of a system at constant pressure is specific heat at constant pressure.
Eenrgy is ability to do work
disorder refet to entropy. Higher the disorder, higher the entropy.
Eenrgy of motion is called kinetic energy.
Thermochemistry deals with energy changes during chemical reactions as well as change in state.
speciific heat is the amount of heat required to rise the temperature of substance by 1deg.c
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.