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77julia77 [94]
2 years ago
6

the half life of a given radioactive isotope is 5 minutes how many grams of 48 gram sample would remain after 20 minutes have el

apsed?
Chemistry
1 answer:
inessss [21]2 years ago
3 0

Answer:

3

Explanation:

the half life of a radioactive isotope is the amount of time one half of the isotope takes to decay

after 5 minutes the mass will be 24

after 10 minutes the mass will be 12

after 15 minutes the mass will be 6

after 20 minutes the mass will be 3

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A 34.53 ml sample of a solution of sulfuric acid, h2s04, reacts with 27.86 ml of 0.08964 m naoh solution. calculate the molarity
Gnoma [55]
The balanced equation between NaOH and H₂SO₄ is as follows
2NaOH + H₂SO₄ ---> Na₂SO₄ + 2H₂O
stoichiometry of NaOH to H₂SO₄ is 2:1
number of moles of NaOH moles reacted = molarity of NaOH x volume
number of NaOH moles = 0.08964 mol/L x 27.86 x 10⁻³ L = 2.497 x 10⁻³ mol
according to molar ratio of 2:1
2 mol of NaOH reacts with 1 mol of H₂SO₄
therefore 2.497 x 10⁻³ mol of NaOH reacts with - 1/2 x 2.497 x 10⁻³ mol of H₂SO₄
number of moles of H₂SO₄ reacted - 1.249 x 10⁻³ mol 
Number of H₂SO₄ moles in 34.53 mL - 1.249 x 10⁻³ mol 
number of H₂SO₄ moles in 1000 mL - 1.249 x 10⁻³ mol / 34.53 x 10⁻³ L = 0.03617 mol 
molarity of H₂SO₄ is 0.03617 M
6 0
3 years ago
In the combustion reaction CH4+2O2 yield CO2 + 2H2Owhich reactant has the greatest rate of disappearance?
Maksim231197 [3]

Answer:

To consume the 2.8 moles of CH4 we need 5.6 moles of O2 since the molar ratio is 1:2. We have only 3 moles of O2 ; therefore, O2 is the limiting reactant.

Explanation:

6 0
3 years ago
Suppose of potassium sulfate is dissolved in of a aqueous solution of sodium chromate. Calculate the final molarity of potassium
dimulka [17.4K]

Answer:

This question is incomplete, here's the complete question:

<em><u>"Suppose 0.0842g of potassium sulfate is dissolved in 50.mL of a 52.0mM aqueous solution of sodium chromate. Calculate the final molarity of potassium cation in the solution. You can assume the volume of the solution doesn't change when the potassium sulfate is dissolved in it. Round your answer to 2 significant digits."</u></em>

Explanation:

Reaction :-

K2SO4 + Na2CrO4 ------> K2CrO4 + Na2SO4

Mass of K2SO4 = 0.0842 g, Molar mass of K2SO4 = 174.26 g/mol

Number of moles of K2SO4 = 0.0842 g / 174.26 g/mol = 0.000483 mol

Concentration of Na2CrO4 = 52.0 mM = 52.0 * 10^-3 M = 0.052 mol/L

Volume of Na2CrO4 solution = 50.0 ml = 50 L / 1000 = 0.05 L

Number of moles of Na2CrO4 = 0.05 L * 0.052 mol/L = 0.0026 mol

Since number of moles of K2SO4 is smaller than number of moles Na2CrO4, so 0.000483 mol of K2SO4 will react with 0.000483 mol of Na2CrO4 will produce 0.000483 mol of K2CrO4.

0.000483 mol of K2CrO4 will dissociate into 2* 0.000483 mol of K^+

Final concentration of potassium cation

= (2*0.000483 mol) / 0.05 L = 0.02 mol/L = 0.02 M

8 0
3 years ago
A scientist collected the data shown in the graph above. How is the graph useful to the scientist?
Vladimir79 [104]
The scientist can analyze that data and help other scientists with his research
7 0
3 years ago
If 2.4 g of n2 gas has a volume of 0.40 l and a pressure of 6.6 atm , what is its kelvin temperature?
Nesterboy [21]

To solve for the absolute temperature, we assume ideal gas behaviour so that we use the equation:

PV = nRT

or T = PV / nR

 

So calculating:

T = [6.6 atm * 0.40 L] / [(2.4g / 28g/mol) * 0.08205746 L atm / mol K]

<span>T = 375.35 K</span>

8 0
3 years ago
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