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3 years ago

Which of the following is true about the concept of half-life?

Chemistry

2 answers:

Reptile [31]3 years ago

8 0

Its A. because it measures the rate of the decay of the isotope

Margaret [11]3 years ago

3 0

it is A Half-life measures the rate of decay of a radioisotope.

I took the test

You might be interested in

How much heat does it take to melt 5.0g solid copper?

Leya [2.2K]

Answer:

$Q=1.04kJ$

Explanation:

Hello,

In this case, for latent heat (phase change) we need to consider the enthalpy associated with the involved process, here, melting or fusion; thus, the enthalpy of fusion of copper is 13.2 kJ/mol, therefore, the heat is computed as:

$Q=m\Delta H_{fus}$

Nevertheless, since the given enthalpy is per mole of copper, we need to use its atomic mass to perform the correct calculation as follows:

$Q=5.0g*\frac{1mol}{63.54}* 13.2\frac{kJ}{mol}\\ \\Q=1.04kJ$

Which is positive as it needs to be supplied to the system.

Best regards.

5 0

3 years ago

Estimate the Calorie content of 65 g of candy from the following measurements. A 15-g sample of the candy is placed in a small a

GrogVix [38]

Answer:

The calorie content of 65g of candy is 326.78 cal

Explanation:

Step 1: Data given

Mass of the candy = 15.00 grams

Mass of the container = 0.325 kg

Mass of water = 1.75kg

0.624 kg at an initial temperature of 15.0°C.

The specific heat of aluminium = 0.22 Cal/kg°C

The specific heat of water = 1 cal/kg°C

Step 2: Calculate calorie content for a 15 gram sample

ΔQ = Σm*c*ΔT

⇒ m = mass in grams

⇒ with c= the specific heat in Cal/kg°C

⇒ with ΔT = T2 -T1 = the change in temperatures in °C

ΔQ = m(bomb) * C(aluminium) * ΔT + m(cup) * C(aluminium) * ΔT + m(H2O) * c(H20) * ΔT

ΔQ = (m(bomb) + m(cup)) * c(aluminium) + m(H2O)*c(H20) ) * ΔT

⇒ with mass of the bomb calorimeter = 0.325 kg

⇒ with mass of the cup = 0.624 kg

⇒ with c(aluminium) = the specific heat of aluminium = 0.22 Cal/kg°C

⇒ with mass of water = 1.75 kg

⇒ with c(water) = the heat capacity of water = 1 Cal/kg°C

⇒ with ΔT = the change in temperature = T2 - T1 = 53.5 - 15.0 = 38.5 °C

ΔQ = 0.325*0.22*38.5 + 0.624*0.22*38.5 + 1.75*1*38.5

ΔQ = ((0.325 + 0.624)*0.22 + 1.75*1)*38.5

ΔQ = 75.41 cal

Step 3: Calculate the calorie content for a 65 gram sample

For a 65g sample the calorie content will be more or less 4x higher than a 15 gram sample:

ΔQ = 75.41 * (65/15) = 326.78 cal

8 0

3 years ago

A thin sheet of iridium metal that is 3.12 cm by 5.21 cm has a mass of 87.2 g and a thickness of 2.360 mm. What is the density o

never [62]

Answer:

Therefore the density of the sheet of iridium is 22.73 g/cm³.

Explanation:

Given, the dimension of the sheet is 3.12 cm by 5.21 cm.

Mass: The mass of an object can't change with respect to position.

The S.I unit of mass is Kg.

Weight of an object is product of mass of the object and the gravity of that place.

Density: The density of an object is the ratio of mass of the object and volume of the object.

$Density =\frac{mass}{volume}$

$=\frac{Kg}{m^3}$ [S.I unit of mass= Kg and S.I unit of m³]

Therefore the S.I unit of density = Kg/m³

Therefore the C.G.S unit of density=g/cm³

The area of the sheet is = length × breadth

=(3.12×5.21) cm²

=16.2552 cm²

Again given that the thickness of the sheet is 2.360 mm =0.2360 cm

Therefore the volume of the sheet is =(16.2552 cm²×0.2360 cm)

=3.8362272 cm³

Given that the mass of the sheet of iridium is 87.2 g.

$Density =\frac{87.2 g}{3.8362272 cm^3}$

=22.73 g/cm³

Therefore the density of the sheet of iridium is 22.73 g/cm³.

5 0

3 years ago

How many moles of each element are in one mole of Sr(HCO,),? (3 points)

Mama L [17]

Answer: 1 mole of strontium, 2 moles of hydrogen, 2 moles of carbon, 6 moles of O

Explanation: i think i’m not sure

3 0

3 years ago

When do you stop writing your electron configurations?

erma4kov [3.2K]

When all the electrons are placed in their orbitals!!!

7 0

3 years ago