The half-life of a particular element is 280 days. what is its decay constant?

Answers

Answer 1

Answer: The formula for decay is
                                      N' = Ne^(-kt)
with N as the initial amount, k as the decay constant, and N' as the final amount. For decay, 280 days is the time it takes for the initial amount N to decay to 1/2N (half its original mass).
                                 1/2A = Ae^(-280k)
                                 1/2    =   e^(-280k)
Solving for k, we will yield
   ln(1/2) = -280k
                                          k = ln(2) / 280 day^-1
                                          k ≈ 2.5 × 10^-3 day^-1

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How much heat is absorbed when 52.39 H2O(l) at 100°C and 101.3 kPa is converted to steam at 100°C? (The molar heat of vaporization of water is40.7 k/mol.)2.09 x 1020O 2.31% 10110O 1.18 x 102 103O 1.11% 1021)
Which is the best description of a molecule?
What is the phase of water at 0.25 atm and 0°C?Water(liquid)Pressure (atm)0.5-0.25Ice(solid)Water vapor(gas)0000Temperature (°C)O A. GasO B. Solid and gasO C. Solid and liquidD. Solid

Ammonium nitrate dissociates in water according to the following equation:43() = 4+()+03−()

When a student mixes 5.00 g of NH4NO3 with 50.0 mL of water in a coffee-cup calorimeter, the temperature of the resultant solution decreases from 22.0 °C to 16.5 °C. Assume the density of water is 1.00 g/ml and the specific heat capacity of the resultant solution is 4.18 J/g·°C.

1) Calculate q for the reaction. You must show your work.

2) Calculate the number of moles of NH4NO3(s) which reacted. You must show your work.

3) Calculate ΔH for the reaction in kJ/mol. You must show your work.

Answers

Answer:

Explanation:

NH₄NO₃ = NH₄⁺ +NO₃⁻

heat released by water = msΔ T

m is mass , s is specific heat and ΔT is fall in temperature

= 50 x 4.18 x ( 22 - 16.5 ) ( mass of 50 mL is 50 g )

= 1149.5 J .

This heat will be absorbed by the reaction above .

q for the reaction = + 1149.5 J

2 )

molecular weight of NH₄NO₃ = 80

No of moles reacted = 5/80 = 1 / 16 moles.

3 )

5 g absorbs 1149.5 J

80 g absorbs 1149.5 x 16 J

= 18392 J

= 18.392 kJ.

= + 18.392 kJ

ΔH = 18.392 kJ / mol

If 1.20 g of aluminum hydroxide reacts with 3.00 g of sulfuric acid, what is the mass of water produced? Al(OH)3(s)+H2SO4(l)→Al2(SO4)3(aq)+H2O(l)

Answers

it would be 342 acid

Write a balanced chemical equation for the standard formation reaction of gaseous dinitrogen tetroxide

Answers

Answer:

$N_2(g)+2O_2(g)\rightarrow N_2O_4(g)$

Explanation:

Hello,

In this case, considering the required product which is dinitrogen tetroxide whose molecular formula is N₂O₄, by considering its formation reaction which is starting by both gaseous nitrogen and oxygen as shown below:

$N_2(g)+O_2(g)\rightarrow N_2O_4(g)$

Nevertheless, it should be balance since four oxygen atoms are present at the right side, thus, we obtain:

$N_2(g)+2O_2(g)\rightarrow N_2O_4(g)$

Best regards.

A 0.1153-gram sample of a pure hydrocarbon was burned in a C-H combustion train to produce 0.3986 gram of CO2and 0.0578 gram of H2O. Determine the masses of C and H in the sample and the percentages of these elements in this hydrocarbon.

Answers

Answer: The mass of carbon and hydrogen in the sample is 0.1087 g and 0.0066 g respectively and the percentage composition of carbon and hydrogen in the sample is 94.27 % and 5.72 % respectively.

Explanation:

The chemical equation for the combustion of hydrocarbon having carbon and hydrogen follows:

$C_xH_y+O_2\rightarrow CO_2+H_2O$

where, 'x' and 'y' are the subscripts of carbon and hydrogen respectively.

We are given:

Mass of $CO_2=0.3986g$

Mass of $H_2O=0.0578g$

Mass of sample = 0.1153 g

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 0.3986 g of carbon dioxide, $(12)/(44)* 0.3986=0.1087g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 0.0578 g of water, $(2)/(18)* 0.0578=0.0066g$ of hydrogen will be contained.

To calculate the percentage composition of a substance in sample, we use the equation:

$\%\text{ composition of substance}=\frac{\text{Mass of substance}}{\text{Mass of sample}}* 100$ ......(1)

For Carbon:

Mass of sample = 0.1153 g

Mass of carbon = 0.1087 g

Putting values in equation 1, we get:

$\%\text{ composition of carbon}=(0.1087g)/(0.1153g)* 100=94.27\%$

For Hydrogen:

Mass of sample = 0.1153 g

Mass of hydrogen = 0.0066 g

Putting values in equation 1, we get:

$\%\text{ composition of hydrogen}=(0.0066g)/(0.1153g)* 100=5.72\%$

Hence, the mass of carbon and hydrogen in the sample is 0.1087 g and 0.0066 g respectively and the percentage composition of carbon and hydrogen in the sample is 94.27 % and 5.72 % respectively.

How is energy transfer connected to your life

Answers

Answer:

Baking, microwave, heating system for your house, water boiler, fridge.

What is a ‘control’ in an experiment?A. A version of the experiment that is unchanged to make sure the experimental data is not due to chance.
B. A person who oversees the experiment to make sure it is following proper procedures.
C. The variable controlled by the scientist to affect the dependent variable.
D. The name for the set of independent and dependent variables that will be controlled by the scientist.

need help asap got 1 minute

Answers

The statement, that describes the ‘control’in an experiment is "the name for the set of independent and dependent variables that will be controlled by the scientist."

What is a control in experiment?

A control is an element in an experiment that remains intact or unaffected by other variables. An experiment or observation aiming to minimise the influence of variables other than the independent variable is referred to as a scientific control. It serves as a standard or point of reference against which other test findings are measured.

In a scientific experiment, an independent variable is the variable that is modified or manipulated in order to assess the effects on the dependent variable. In a scientific experiment, the dependent variable is the variable that is being tested and measured. The designation given to the set of independent and dependent variables that the scientist will regulate.

Hence the correct option is D.

Learn more about controlin an experiment here

https://brainly.in/question/19374703

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D. The name for the set of independent and dependent variables that will be controlled by the scientist.

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