Please help, very confused. (Chem)?
Some explanations would be nice too! Strontium-90 is a radioisotope that will decrease in mass by one-half every 29 years. How many years will it take a 10.0-gram sample of strontium-90 to decay to 2.50 grams? 1 14.5 29 58 A rock has 12.5 percent of its original amount of potassium-40 remaining in it. Potassium-40 has a half-life of 1.25 billion years. How long ago was the rock formed? 1.25 billion years ago 2.5 billion years ago 3.75 billion years ago 5 billion years ago A radioactive isotope has a half-life of 2 years. What fraction of isotope is left after 2 years? one over one one half one fourth one eighth Which of the following nuclear equations show beta decay? 222 over 86 Rn yields 218 over 84 Po 214 over 84 Po yields 210 over 82 Pb 14 over 6 C yields 14 over 7 N 6 over 2 He yields 6 over 3 Li
Can you help me on some chemistry homework, I am so confused? Half lifes?
1.A thyroid scan used 320 mCi of I−123, which has a half-life of 13.2 h. How long, in hours, would it take for the activity to be reduced to 20 mCi? Express your solution in sig figs. How would you go about doing this? Are you suposed to divide the 320 by 2 a certain amount of times to get the half life? 2.A 64-μCi sample of P-33 decays to 4.0 μCi in 100 days. What is the half-life, in days, of P-33? How do you solve this?What does the y looking symbol next to the ci mean? I have a terrible instructor that does not go over any of this and I can not find it in the book does that mean gamma? 3. A 124mg sample of technetium-99 m is used for a diagnostic test.If technetium-99 m has a half-life of 6.0 hr , how much of the technetium-99 m sample remains 24.0hr after the test? It says the half is 6 hours. and 24/6 is 4. Would you divide the 124mg in half 4 times? 4.The half-life for the radioactive decay of Ce-141 is 32.5 days. If a sample has an activity of 5.0μCi after 65 days have elapsed, what was the initial activity, in microcuries, of the sample? What does the y symbolize next to the 5.0yCi.. Since the sample has a activity of5.0μC after 65 days, what would you use that information for. Any help would be appreciated, thank you.
Chemistry help Half-life!?
Hi, I am confused on half lifes. can you give me the answer to this problem PLUS the steps/explanations of how you done your work. I tried to read the chem book but i don't get it :O Heres the question Tin-129 is radioactive and has a half life of 2.23 minutes. what % of a sample would be left after 4.78 minutes.
Help with chemistry homework?
Don't be confused by the 10^23, you can even drop that till the end. A half life is the amount of time it takes for half of a reactive substance to degrade. So after 1 half-life, only half of the original mount will remain. There are formulas for this, but your question is an easy one. If the half life is 4 days, and 12 days pass, then 3 half lives have passed. That means 5.85 will be divided by 2 a total of 3 times. SO 5.85/2= 2.925 2.925/2= 1.4625 1.4625/2= 0.73125 now just throw the 10^23 back on... 0.73125*10^23 = 7.3125*10^22 atoms.
I need help with chemistry. lots of questions due and idk how to do them.?
Determine the oxidation number of each atom in CH4 THe half life of thorium-234 is 24.10 days. how many days until only one-sixteenth of a 52.0g sample of thorium remains? what is the hydrogen concentration in a fruit juice that has a PH of 3.3 the types of forces experienced by nonpolar substances are called ____ which are the weakest IMF. ____ substances experience ____and ____ _____ forces. i have alot more. but will try to do them on my own later. if you could explain to me how to do the problem, that would be helpful because i have more than one of each. thanks! (:
Deriving Half-Life question in chemistry and math?
this is really confusing. I am currently taking both calculus and chemestry right and we are doing half-life. For calculus it was growth/decay problems while for chem its Reaction problems. What is weird to me is that when we derive HL in calculus, it was -ln2/k while in chemistry its ln2/k. There is a negative sign stuck in front of the first one. This is really confusing to me becuase ln2/k in calculus is doubling time. So can someone explain to me which one is correct and which one is not. Calculus: 1=2Ce^kt Ln1/2= Kt Ln1 - Ln2 = Kt (ln1=0) -ln2= Kt -ln2/k = HL while chem: ln[A]o / Ln[A]t = kt t= t1/2 and [A]t = 1/2[A]o by substituting ln [A]o / (1/2[A]o) = kt Ln[A]o cancels out and left with Ln 1/(1/2) bring 1/2 up and we have: Ln2/k = HL as you can see one has negative sign and the other dont
Some Chemistry help, please?
I have done the entire homework assignment #1 by myself except for the last page. Here are the 2 questions: The half-life for the radioactive decay of C−14 is 5730 years. How long will it take for 25% of the C−14 atoms in a sample of C−14 to decay? (Express your answer using two significant figures) If a sample of C−14 initially contains 1.4mmol of C−14, how many millimoles will be left after 2230 years? (Express your answer using two significant figures.) Please explain them to me; I am hoping to get an A on the next exam and I'm sure he will ask us problems like these. Thanks.
How can I learn Chemistry easily?
I have completed my intermediate so I'll be answering according to it.chemistry is the toughest subject during my schooling and I used to get fever before the day of exam, for the fear I have on chemistry.As I have chosen MPC, chemistry is a compulsory subject and I have to study somehow. Even the subject depth changes to a great extent from schooling to college and my fear got increased. But due to lecturer who came for teaching chemistry inspired me a lot tough he didn't pay Any special attention on me, but his words in the class inspired me.Without my notice, I started liking the subject. I used to revise what I've learn and used to study new topics everyday. Revision on day to day basis is very very important.Try to remember exceptional cases in chemistry.always 1St read text book line to line without leaving single word. Mark all important points. Study the text books as many times as you can.Try to spend more time on chemistry if your too weak in the subject. But once you start liking the subject I promise you gonna have great time. You enjoy yourself reading chemistry.Listen to classes is very important because you are going to learn 25% of the topic there itself.Try to answer the questions at the back of the lesson so that you can have your own self assessment.You should have great memory power because you should remember lot of things at once which seems to be confusing.There is no simple way to learn anything. Your own hardwork makes it simple day by day. And after completing intermediate chemistry is my favorite subject which I love to read.All the best.Hope it helps you.