All categories

3 years ago

Did scallops live before or after dinosaurs according to a fossil record

Chemistry

2 answers:

Burka [1]3 years ago

4 0

Yes they libed before the dinasours and during the jurassic (triassic period).

Delvig [45]3 years ago

4 0

According to fossil records scallops live before dinosaurs

You might be interested in

a sample of gas measures 5 liters at 1 atm. to change the volume to a 3.5 liters at constant temperature what pressure must be a

Scorpion4ik [409]

Answer:

0.7atm

Explanation:

3.5/5 because constant temperature

8 0

3 years ago

A scientist has a container with a substance inside. At first, the molecules in the substance move away from each other. Later,

Vera_Pavlovna [14]

Answer:

Base on the properties the substances possess the substance change phase from gas to liquid.

Explanation:

Generally, matter can exist in three phase namely liquid , solid and gas. The scientist has a container with a substance inside.

At first the substance moves away from each other . This means the substance was first in the gas phase . Gas molecules, because of the energy they possess , it can move rapidly and randomly and most at times move away from each other . The gas molecules tends to fill the whole volume of the container and the shape of gases are indefinite.

Later the molecules move around each other. This is a property of a liquid . A substance in liquid phase have the ability to move freely but they stay together because of the force of attraction holding them together . The substance only have the ability to move around each other because the forces holding them together won't allow them to move apart.

Base on the properties the substances possess the substance change phase from gas to liquid.

5 0

3 years ago

Read 2 more answers

The gas-phase reaction follows an elementary rate law and is to be carried out first in a PFR and then in a separate experiment

astraxan [27]

Answer:

The activation energy is $=8.1\,kcal\,mol^{-1}$

Explanation:

The gas phase reaction is as follows.

$A \rightarrow B+C$

The rate law of the reaction is as follows.

$-r_{A}=kC_{A}$

The reaction is carried out first in the plug flow reactor with feed as pure reactant.

From the given,

Volume "V" = $10dm^{3}$

Temperature "T" = 300 K

Volumetric flow rate of the reaction $v_{o}=5dm^{3}s$

Conversion of the reaction "X" = 0.8

The rate constant of the reaction can be calculate by the following formua.

$V= \frac{v_{0}}{k}[(1+\epsilon )ln(\frac{1}{1-X}-\epsilon X)]$

Rearrange the formula is as follows.

$k= \frac{v_{0}}{V}[(1+\epsilon )ln(\frac{1}{1-X}-\epsilon X)]............(1)$

The feed has Pure A, mole fraction of A in feed $y_{A_{o}}$ is 1.

$\epsilon =y_{A_{o}}\delta$

$\delta$ = change in total number of moles per mole of A reacte.

$=1(2-1)=1$

Substitute the all given values in equation (1)

$k=\frac{5m^{3}/s}{10dm^{3}}[(1+1)ln \frac{1}{1-0.8}-1 \times 0.8] = 1.2s^{-1}$

Therefore, the rate constant in case of the plug flow reacor at 300K is $1.2s^{-1}$

The rate constant in case of the CSTR can be calculated by using the formula.

$\frac{V}{v_{0}}= \frac{X(1+\epsilon X)}{k(1-X)}.............(2)$

The feed has 50% A and 50% inerts.

Hence, the mole fraction of A in feed $y_{A_{o}}$ is 0.5

$\epsilon =y_{A_{o}}\delta$

$\delta$ = change in total number of moles per mole of A reacted.

$=0.5(2-1)=0.5$

Substitute the all values in formula (2)

$\frac{10dm^{3}}{5dm^{3}}=\frac{0.8(1+0.5(0.8))}{k(1-0.8)}=2.8s^{-1}$

Therefore, the rate constant in case of CSTR comes out to be $2.8s^{-1}$

The activation energy of the reaction can be calculated by using formula

$k(T_{2})=k(T_{1})exp[\frac{E}{R}(\frac{1}{T_{1}}-\frac{1}{T_{2}})]$

In the above reaction rate constant at the two different temperatures.

Rearrange the above formula is as follows.

$E= R \times(\frac{T_{1}T_{2}}{T_{1}-T_{2}})ln\frac{k(T_{2})}{k(T_{1})}$

Substitute the all values.

$=1.987cal/molK(\frac{300K \times320K}{320K \times300K})ln \frac{2.8}{1.2}=8.081 \times10^{3}cal\,mol^{-1}$

$=8.1\,kcal\,mol^{-1}$

Therefore, the activation energy is $=8.1\,kcal\,mol^{-1}$

8 0

3 years ago

When reactants and products are being formed at an equal rate in a chemical reaction, the ____. a. reaction is endergonic b. fre

attashe74 [19]

<h2>The answer is option b "free energy is zero"</h2>

Explanation

The reaction that has negative free energy are called exergonic reactions that means the reactants have more free energy than the product formed.
The reaction that has positive free energy are called endergonic reactions that means the final state or the products formed have more free energy than the initial state or the reactants.
The reaction that has zero free energy occurs when the free energy of both reactants and the products are same hence the rate of formation of products and reactants are equal.
Therefore, when reactants and products are being formed at an equal rate the free energy is zero.

3 0

3 years ago

Hey, I’ll give brainliest. Just please help.

Andre45 [30]

Answer:

Explanation:

8 0

3 years ago