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
Vesna [10]
2 years ago
10

If you have 100 grams of a radioactive isotope with a half life of 10 years how much of the isotope will you have left after 20

years
Chemistry
1 answer:
Cerrena [4.2K]2 years ago
3 0

Hey there!

A half-life means after a certain amount of time, half of that substance will be gone/changed after that time.

There are two half lives in 20 years because 20 ÷ 10 = 2.

So, we divide the 100g sample in half 2 times.

100 ÷ 2 = 50

50 ÷ 2 = 25

There will be 25g of the radioactive sample remaining after two half lives.

Hope this helps!

You might be interested in
A family takes a summer vacation to Florida. They drive for 8 hours before stopping at a hotel for the night. They
andrezito [222]

Average speed of the trip = 52 km/hr

<h3>Further explanation  </h3>

Distance is the length traveled by an object within a certain of time .

Average speed = total distance/total amount of  time ,

Can be formulated :

\tt S(speed)=\dfrac{D}{T}

Total distance travelled : 1560 km

Total time : 8 hr + 12 hr + 10 hr = 30 hr

\tt avg.speed=\dfrac{tot~D}{tot~T}\\\\avg.speed=\dfrac{1560}{30}\\\\avg.speed=52~km/hr

7 0
3 years ago
Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol SrO (s) + CO₂ (g) → SrCO₃ (s) ∆H° = -234 kJ/mol CO₂ (g) → C(
kkurt [141]

<u>Answer:</u> The \Delta H^o_{rxn} for the reaction is 72 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

2SrCO_3(s)\rightarrow 2Sr(s)+2C(s)+3O_2(g)      \Delta H^o_{rxn}=?

The intermediate balanced chemical reaction are:

(1) 2Sr(s)+O_2(g)\rightarrow 2SrO(s)    \Delta H_1=-1184kJ

(2) SrO(s)+CO_2(g)\rightarrow SrCO_3(s)     \Delta H_2=-234kJ      ( × 2)

(3) CO_2(g)\rightarrow C(s)+O_2(g)     \Delta H_3=394kJ    ( × 2)

The expression for enthalpy of the reaction follows:

\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[2\times (-\Delta H_2)]+[2\times (\Delta H_3)]

Putting values in above equation, we get:

\Delta H^o_{rxn}=[(1\times (-1184))+(2\times -(-234))+(2\times (394))]=72kJ

Hence, the \Delta H^o_{rxn} for the reaction is 72 kJ.

4 0
3 years ago
Both of the silicon-chlorine single bonds in sicl4 are polar. in which direction should the polarity arrows point?
o-na [289]

Тhe arrow should point to the atom with greater electrical energy, in the case of the chlorine atoms
6 0
3 years ago
1. NaOH mass of a solution of 200g in which its percentage is 25%. What mass of sulfuric acid solution is needed to completely n
Ede4ka [16]

Answer:

m_{H2SO4 = 61.25 g

m_{Na2SO4} = 88.75 g

Explanation:

m_{NaOH} = \frac{200 . 25 }{100} = 50 g

⇒ n_{NaOH} = \frac{50}{40} = 1.25 (moles)

2NaOH + H2SO4 ⇒ Na2SO4 + 2H2O

   2        :     1           :      1         :    2

 1.25                                                       (moles)

⇒  n_{H2SO4} = 1.25 × 1 ÷ 2 = 0.625 (moles) ⇒ m_{H2SO4} = 0.625 × 98 = 61.25 g

    n_{Na2SO4} = 1.25 × 1 ÷ 2 = 0.625 (moles) ⇒m_{Na2SO4} = 0.625 × 142 = 88.75 g

4 0
3 years ago
Balance the following: ___ AlBr3+ ___ K---&gt; ___KBr+ ___ Al
Nataliya [291]
___AlBr3 + ___K -> ___KBr + ___ Al

1 AlBr3 + 3K -> 3KBr + 1 Al

hope this helps............
6 0
3 years ago
Other questions:
  • In the experiment, you added water to the reaction vessel after the reaction was complete, but we did not discuss why. Based on
    5·1 answer
  • What is the name of the compound with the formula N2O4?​
    9·1 answer
  • The ease with which a raw material can be molded , flattened , or bent is known as its ?
    15·2 answers
  • Here this is a clearer photo so what should I do
    5·1 answer
  • With all the coefficient set to 1, how can you tell that the equation is not balanced?
    10·1 answer
  • The temperature of 200 mL of gas
    14·1 answer
  • Which chemical substance has the highest melting point? a) gold b) water c) oxygen d) mercury
    5·2 answers
  • Defferent between crysttiline solid and amerphus solid​
    11·1 answer
  • 14) For the reaction P4(s) + 6 Hz(9) — 4 PH3(g)
    13·1 answer
  • What is the average dose of radiation that most people are exposed to every year not including dental or medical personnel deali
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!