Which radioactive isotope is commonly used to date wooden artifacts? carbon-14 (14c) uranium-238 (238u) potassium-40 (40k) argon-38 (38ar)

Scientists commonly use carbon-14 (¹⁴C) to date wooden artifacts.

The ¹⁴C:¹²C ratio is constant in living plants. When they die, the ¹⁴C decays, so the ratio changes. The half-life for the for the decay is 5730 a, so scientists can work backwards and calculate how long ago the plant died. The method is good for samples up to 50 000 a old.

²³⁸U gradually decays to lead. The U:Pb ratio can give the age of a rock that is between 100 000 a and 1 200 000 a old.

³⁸Ar can date certain rocks that are between 200 000 a and 4 000 000 a old.

⁴⁰K decays to ⁴⁰Ar. Geologists can use K:Ar dating for rocks up to four billion years old.

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

a) the particles of the chair are strongly held together.