Determine whether each statement is a description of a physical property or a chemical property.

The time necessary for the decay of one- half sample of a radioactive substance is a _____. mass defect daughter half life nucli

Mazyrski [523]

Answer: half life

Explanation: Radioactive decay follows first order kinetics and the time required for the decay of a radioactive material is calculated as follows:

$t=\frac{2.303}{k}\hspace{1mm}log\frac{x}{a}$

t= time required

k= disintegration constant

x= amount of substance left after time t

a= initial amount of substance

when one half of the sample is decayed, one half of the sample remains and t can be represented as $t_{1/2}$

at $t= t_{1/2}$ , $x=\frac{a}{2}$

$t_{1/2}=\frac{2.303}{k}\hspace{1mm}log\frac{a/2}{a}$

$t_{1/2}=\frac{0.693}{k}$

3 0

2 years ago

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Consider the following reaction: CO(g)+2H2(g)⇌CH3OH(g) Kp=2.26×104 at 25 ∘C. Calculate ΔGrxn for the reaction at 25 ∘C under eac

valentinak56 [21]

Answer : The value of $\Delta G_{rxn}$ is, $8.867kJ/mole$

Explanation :

The formula used for $\Delta G_{rxn}$ is:

$\Delta G_{rxn}=\Delta G^o+RT\ln Q$ ............(1)

where,

$\Delta G_{rxn}$ = Gibbs free energy for the reaction

$\Delta G_^o$ = standard Gibbs free energy

R = gas constant = 8.314 J/mole.K

T = temperature = $25^oC=273+25=298K$

Q = reaction quotient

First we have to calculate the $\Delta G_^o$ .

Formula used :

$\Delta G^o=-RT\times \ln K_p$

Now put all the given values in this formula, we get:

$\Delta G^o=-(8.314J/mole.K)\times (298K)\times \ln (2.26\times 10^{4})$

$\Delta G^o=-24839.406J/mole=-24.83\times 10^3J/mole=-24.83kJ/mole$

Now we have to calculate the value of 'Q'.

The given balanced chemical reaction is,

$CO(g)+2H_2(g)\rightarrow CH_3OH(g)$

The expression for reaction quotient will be :

$Q=\frac{(p_{CH_3OH})}{(p_{CO})\times (p_{H_2})^2}$

In this expression, only gaseous or aqueous states are includes and pure liquid or solid states are omitted.

Now put all the given values in this expression, we get

$Q=\frac{(1.4)}{(1.2\times 10^{-2})\times (1.2\times 10^{-2})^2}$

$Q=8.1\times 10^{5}$

Now we have to calculate the value of $\Delta G_{rxn}$ by using relation (1).

$\Delta G_{rxn}=\Delta G^o+RT\ln Q$

Now put all the given values in this formula, we get:

$\Delta G_{rxn}=-24.83kJ/mole+(8.314\times 10^{-3}kJ/mole.K)\times (298K)\ln (8.1\times 10^{5})$

$\Delta G_{rxn}=8.867\times 10^3J/mole=8.867kJ/mole$

Therefore, the value of $\Delta G_{rxn}$ is, $8.867kJ/mole$

3 0

2 years ago

What does in the zone mean in a picture and a idiom? (Please answer this as soon a possible!)

julia-pushkina [17]

If you are in the zone, you are happy or excited because you are doing something very skilfully and easily.

5 0

2 years ago

Describe the difference between a ball-and-stick model and a space-filling model of a compound.

Lisa [10]

A space-filling model shows the relative amount of space each atom takes up. In other words, a space-filling model can show relative sizes of atoms. However, unlike ball-and-stick or structural models, space-filling models do not show bond lengths clearly. Bonds are not really like sticks in a ball-and-stick model.

4 0

2 years ago

What is volume? What instrument is used to measure liquid volume? What formula is used to calculate the volume of a solid object

sertanlavr [38]

Answer:

Volume is the amount of space that a substance occupies. A graduated cylinder is used to measure liquid volume. The formula used to calculate the volume of a solid object is = L x W x H

Explanation:

8 0

2 years ago