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
Elena-2011 [213]
2 years ago
7

The radioisotope radon-222 has a half life of 3.8 days. How much of a 10 gram sample of radon-222 would be left after 15.2 days?

Chemistry
1 answer:
djyliett [7]2 years ago
4 0

Answer:

0.625 g

Explanation:

Given data:

Half life of radon-222 = 3.8 days

Total mass of sample = 10 g

Mass left after 15.2 days = ?

Solution:

Number of half lives = T elapsed / Half life

Number of half lives = 15.2 / 3.8

Number of half lives = 4

At time zero = 10 g

At first half life = 10 g/2 = 5 g

At 2nd half life = 5 g/ 2= 2.5 g

At third half life = 2.5 g/2 = 1.25 g

At 4th half life = 1.25 g/2 = 0.625 g

You might be interested in
When you combine 50.0 mL of 0.100 M AgNO3 with 50.0 mL of 0.100 M HCl in a coffee-cup calorimeter, the temperature changes from
RideAnS [48]

Answer : The enthalpy of reaction (\Delta H_{rxn}) is, 67.716 KJ/mole

Explanation :

First we have to calculate the moles of AgNO_3 and HCl.

\text{Moles of }AgNO_3=\text{Molarity of }AgNO_3\times \text{Volume}=(0.100mole/L)\times (0.05L)=0.005mole

\text{Moles of }HCl=\text{Molarity of }HCl\times \text{Volume}=(0.100mole/L)\times (0.05L)=0.005mole

Now we have to calculate the moles of AgCl formed.

The balanced chemical reaction will be,

AgNO_3(aq)+HCl(aq)\rightarrow AgCl(s)+HNO_3(aq)

As, 1 mole of AgNO_3 react with 1 mole of HCl to give 1 mole of AgCl

So, 0.005 mole of AgNO_3 react with 0.005 mole of HCl to give 1 mole of AgCl

The moles of AgCl formed  = 0.005 mole

Total volume of the solution = 50.0 ml + 50.0 ml = 100.0 ml

Now we have to calculate the mass of solution.

Mass of the solution = Density of the solution × Volume of the solution

Mass of the solution = 1.00 g/ml × 100.0 ml = 100 g

Now we have to calculate the heat.

q=m\times C\Delta T=m\times C \times (T_2-T_1)

where,

q = heat

C = specific heat capacity = 4.18J/g^oC

m = mass = 100 g

T_2 = final temperature = 24.21^oC

T_1 = initial temperature = 23.40^oC

Now put all the given values in the above expression, we get:

q=100g\times (4.18J/g^oC)\times (24.21-23.40)^oC

q=338.58J

Now  we have to calculate the enthalpy of the reaction.

\Delta H_{rxn}=\frac{q}{n}

where,

\Delta H_{rxn} = enthalpy of reaction = ?

q = heat of reaction = 338.58 J

n = moles of reaction = 0.005 mole

Now put all the given values in above expression, we get:

\Delta H_{rxn}=\frac{338.58J}{0.005mole}=6771.6J/mole=67.716KJ/mole

Conversion used : (1 KJ = 1000 J)

Therefore, the enthalpy of reaction (\Delta H_{rxn}) is, 67.716 KJ/mole

4 0
3 years ago
Weight in grams of NaCl
Allisa [31]

Answer: 58.44g

Explanation: The molar mass of NaCl is 58.44g.

7 0
3 years ago
Read 2 more answers
Explain the difference between an endothermic and an exothermic reaction using the concepts of potential energy, stability, and
kakasveta [241]
An Exothermic reaction releases energy into the surroundings and so the products have more potential energy then the reactants. The enthalpy change is a negative value. Whereas, an endothermic reaction involves the absorption of energy into the system and so the reactants have more potential energy than the products. The enthalpy change is a positive value. This is clearly represented in energy profile diagrams.
4 0
3 years ago
Help??
kvasek [131]

Answer:

Mass of sodium chloride decomposed = 24.54 g

Explanation:

Given data:

Mass of sodium chloride decomposed = ?

Mass of chlorine gas formed = 15 g

Solution:

Chemical equation:

2NaCl      →         2Na + Cl₂

Number of moles of Cl₂:

Number of moles = mass/molar mass

Number of moles = 15 g/ 71 g/mol

Number of moles = 0.21 mol

Now we will compare the moles of Cl₂ with NaCl from balance chemical equation.

                    Cl₂            :              NaCl

                      1              :                2

                      0.21         :            2×0.21 = 0.42 mol

Mass of Sodium chloride decompose:

Mass = number of moles × molar mass

Mass = 0.42 mol × 58.44 g/mol

Mass = 24.54 g

4 0
2 years ago
300×175<br> Express your answer using the correct number of significant figures.
icang [17]

Answer:

300×175=52500

Explanation:

caculator

3 0
3 years ago
Other questions:
  • Simple machines make work easier. You must lift and move this load of soil for your parents. It is heavy! You are using two simp
    15·1 answer
  • #1: Which of the following statements is true?
    14·2 answers
  • Waves with the longest wavelengths have the ___________ frequency and the ___________ energy.
    10·1 answer
  • What is the correct formula for potassium sulfite? khso khso4 k2so4 k2so3
    11·2 answers
  • How many atoms are in 3.47 moles of C2H2? Please show work.
    11·1 answer
  • 1. What volume will 0.710 moles of nitrogen gas occupy at STP?
    8·1 answer
  • What is the ph of a solution that has 0.075 m ch3cooh and 0.050m nach3coo present? ka for acetic acid = 1.80 x 10-5?
    14·1 answer
  • HCI
    6·2 answers
  • What is 15 /2.343*233+2341
    15·2 answers
  • Nuclear power plants use a fission reaction of uranium to generate heat to power a generator. A fission reaction is a chain reac
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!