1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
sweet [91]
3 years ago
12

Carbon -11 is a radioactive isotope of carbon. It’s half life is 20 minutes. What amount of the initial mass of 70.0g of C -11 a

toms in a sample will be left after 80 minutes
Chemistry
1 answer:
dusya [7]3 years ago
6 0

Answer:

4.38g

Explanation:

70.0/2 = 35g - 20 mins

35/2 = 17.5g - 40 mins

17.5/2 = 8.75g - 60 mins

8.75/2 = 4.375g - 80 mins

You might be interested in
A 0.1510 gram sample of a hydrocarbon produces 0.5008 gram CO2 and 0.1282 gram H2O in combustion analysis. Its
Over [174]
In a combustion of a hydrocarbon compound, 2 reactions are happening per element:

C + O₂ → CO₂
2 H + 1/2 O₂ → H₂O

Thus, we can determine the amount of C and H from the masses of CO₂ and H₂O produced, respectively.

1.) Compute for the amount of C in the compound. The data you need to know are the following:
Molar mass of C = 12 g/mol
Molar mass of CO₂ = 44 g/mol
Solution:
0.5008 g CO₂*(1 mol CO₂/ 44 g)*(1 mol C/1 mol CO₂) = 0.01138 mol C
0.01138 mol C*(12 g/mol) = 0.13658 g C

Compute for the amount of H in the compound. The data you need to know are the following:
Molar mass of H = 1 g/mol
Molar mass of H₂O = 18 g/mol
Solution:
0.1282 g H₂O*(1 mol H₂O/ 18 g)*(2 mol H/1 mol H₂O) = 0.014244 mol H
0.014244 mol H*(1 g/mol) = 0.014244 g H

The percent composition of pure hydrocarbon would be:
Percent composition = (Mass of C + Mass of H)/(Mass of sample) * 100
Percent composition = (0.13658 g + 0.014244 g)/(<span>0.1510 g) * 100
</span>Percent composition = 99.88%

2. The empirical formula is determined by finding the ratio of the elements. From #1, the amounts of moles is:

Amount of C = 0.01138 mol
Amount of H = 0.014244 mol

Divide the least number between the two to each of their individual amounts:
C = 0.01138/0.01138 = 1
H = 0.014244/0.01138 = 1.25

The ratio should be a whole number. So, you multiple 4 to each of the ratios:
C = 1*4 = 4
H = 1.25*4 = 5

Thus, the empirical formula of the hydrocarbon is C₄H₅.

3. The molar mass of the empirical formula is

Molar mass = 4(12 g/mol) + 5(1 g/mol) = 53 g/mol
Divide this from the given molecular weight of 106 g/mol
106 g/mol / 53 g/mol = 2
Thus, you need to multiply 2 to the subscripts of the empirical formula.

Molecular Formula = C₈H₁₀

4 0
3 years ago
Were are electrons located
lukranit [14]
Electrons are found in the cloud that's surrounded the nucleus of an atom 
8 0
3 years ago
Read 2 more answers
Question 21 of 25
RideAnS [48]

Answer:

7

Explanation:

7 0
3 years ago
What is the [H+] of a solution with a pH of 3? Use a scientific calculator.
Mariulka [41]

Answer:

1 x 10⁻³.

Explanation:

∵ pH = - log[H⁺]

3 = - log[H⁺].

log[H⁺] = -3.

∴ [H⁺] = 1 x 10⁻³.

3 0
3 years ago
Answer the boxes in the image
pochemuha

Answer: the c thingy is where you be like burgundy sauce then be like racial slair is what it mean's so the name thingy

Explanation:

7 0
3 years ago
Other questions:
  • Determine Z and V for steam at 250°C and 1800 kPa by the following: (a) The truncated virial equation [Eq. (3.38)] with the foll
    13·1 answer
  • S + HNO3 = H2SO3 + N2O
    10·1 answer
  • A 25.00-ml sample of propionic acid, hc3h5o2, of unknown concentration was titrated with 0.141 m koh. the equivalence point was
    10·1 answer
  • What are some chemical properties of a rock?
    12·1 answer
  • A chemist adds of a copper(II) sulfate solution to a reaction flask. Calculate the mass in kilograms of copper(II) sulfate the c
    11·1 answer
  • Help asap, testining
    8·1 answer
  • What is a proper adjective?
    8·1 answer
  • Explain why the nucleus of an atom has a positive electrical charge.
    11·1 answer
  • Complete question and balance answer. If anyone can help I’d appreciate it
    12·1 answer
  • Identify the correct formula for each of the following acids. Click here to use the common polyatomic ion sheet if needed.
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!