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GrogVix [38]
3 years ago
10

Isotope b has a half-life of 3 days. a scientist measures out 100 grams of this substance. after 6 days has passed, the scientis

t reexamines the sample.
Chemistry
1 answer:
Brilliant_brown [7]3 years ago
6 0
So half life is the time taken for a sample to decay to half its original mass, its a constant and applies to any original mass, it could be 5g or 1kg, it will take the same amount of time for the original mass to half. In this case the half life is 3 days.

After 3 days the sample will be at half its original mass, now 50g. 

Now we can treat the 50g as if its a new sample. After another 3 days (6 days in total) there will be half of 50g left, = 25g. 


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Urgent help please!!
sveta [45]

Answer:

1. 2.1 moles of Mg

2. 0.72 mole of Mg(OH)2

Explanation:

1. We'll begin by writing the balanced equation for the reaction. This is given below:

3Mg + 2AlBr3 —> 3MgBr2 + 2Al

From the balanced equation above, 3 moles of Mg reacted to produce 2 moles of Al.

Therefore, Xmol of Mg will react to produce 1.4 moles of Al i.e

Xmol of Mg = (3 x 1.4)/2

Xmol of Mg = 2.1 moles.

Therefore, 2.1 moles of Mg is required to 1.4 moles of Al.

2. We'll begin by calculating the number of mole in 26g of water, H2O.

This is illustrated below:

Molar mass of H2O = (2x1) + 16 = 18g/mol

Mass of H2O = 26g

Number of mole of H2O =?

Mole = Mass /Molar Mass

Number of mole of H2O = 26/18

Number of mole of H2O = 1.44 moles

Next, we shall write the balanced equation for the reaction. This is given below:

2HNO3 + Mg(OH)2 —> Mg(NO3)2 + 2H2O

Finally, we can obtain the number of mole of Mg(OH)2 used in the reaction as follow:

From the balanced equation above,

1 mole of Mg(OH)2 reacted to produce 2 mole of H2O.

Therefore, Xmol of Mg(OH)2 will react to produce 1.44 moles of H2O i.e

Xmol of Mg(OH)2 = (1 x 1.44)/2

Xmol of Mg(OH)2 = 0.72 mole.

Therefore, 0.72 mole of Mg(OH)2 was used in the reaction.

3 0
3 years ago
Which of the following statements about protons are true?
attashe74 [19]
The second on it true
4 0
3 years ago
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How many protons, electrons, and neutrons does 1 H+ isotope contain
nlexa [21]
<h3>Answer:</h3>

H+ contains 1 proton, 0 neutrons, 0 electrons.

<h3>Explanation:</h3>
  • An atom is the smallest particle of an element that can take part in a chemical reaction.
  • Atoms are made of sub-atomic particles neutrons and protons found in the nucleus and electrons found in the energy levels.
  • A hydrogen atom contains 1 proton and 0 neutrons in the nucleus and 1 electron in the energy levels.
  • A hydrogen atom loses an electron to form an ion with 1 proton, 0 neutron and 0 electron.
6 0
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The volume of a gas at 2.0 atm is 3.0 L. What is the volume of the gas at 1.5 atm at the same temperature?
pshichka [43]

Answer:

4 L

Explanation:

Ideal gas law is P1V1T2=P2V2T1

V2=P1V1/P2

T is not necessary to add since it is constant.

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