There are three types of symbiotic relationships. They include which of the following?

Who was the most important scientist in the development of the Modern Atomic Theory?

-BARSIC- [3]

Answer:

John Dalton, an English chemist, meteorologist, and physicists, was best known for his development of the modern atomic theory

Explanation:

4 0

4 years ago

How to draw Hess' Cycle for this question ?

NISA [10]

Answer : The standard enthalpy of formation of ethylene is, 51.8 kJ/mole

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The formation reaction of $C_2H_4$ will be,

$2C(s)+2H_2(g)\rightarrow C_2H_4(g)$ $\Delta H_{formation}=?$

The intermediate balanced chemical reaction will be,

(1) $C_2H_4(g)+3O_2(g)\rightarrow 2CO_2(g)+2H_2O(l)$ $\Delta H_1=-1411kJ/mole$

(2) $C(s)+O_2(g)\rightarrow CO_2(g)$ $\Delta H_2=-393.7kJ/mole$

(3) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l)$ $\Delta H_3=-285.9kJ/mole$

Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equations, we get :

(1) $2CO_2(g)+2H_2O(l)\rightarrow C_2H_4(g)+3O_2(g)$ $\Delta H_1=+1411kJ/mole$

(2) $2C(s)+2O_2(g)\rightarrow 2CO_2(g)$ $\Delta H_2=2\times (-393.7kJ/mole)=-787.4kJ/mole$

(3) $2H_2(g)+2O_2(g)\rightarrow 2H_2O(l)$ $\Delta H_3=2\times (-285.9kJ/mole)=-571.8kJ/mole$

The expression for enthalpy of formation of $C_2H_4$ will be,

$\Delta H_{formation}=\Delta H_1+\Delta H_2+\Delta H_3$

$\Delta H=(+1411kJ/mole)+(-787.4kJ/mole)+(-571.8kJ/mole)$

$\Delta H=51.8kJ/mole$

Therefore, the standard enthalpy of formation of ethylene is, 51.8 kJ/mole

7 0

3 years ago

When rubidium metal is exposed to air, two atoms of rubidium, Rb, combine with one atom

Eddi Din [679]

2.1653 g

Explanation:

The molar mass of Rubidium is;

85.468 g/mol

Therefore the moles of Rubidium that reacted with oxygen is;

1.98 / 85.468

= 0.0232 moles

If every two moles of Rubidium reacts with one mole of oxygen then the amount of oxygen consumed in the chemical reaction is;

0.5 * 0.0232

= 0.0116 moles

The molar mass of an oxygen atom is 16 g/mole. Then the amount of O in grams consumed is;

0.0116 * 16

=0.1853 g

The final weight of the Rubidium II Oxide is;

1.98 + 0.1853

= 2.1653 g

8 0

3 years ago

Which of the following molecules would be the best hydrogen bond donor?

leva [86]

Answer: Option (d) is the correct answer.

Explanation:

When a hydrogen atom comes in contact with an electronegative atom then it results in the formation of a chemical bond.

More is the electronegativity of combining atom, more stronger will be the bond with hydrogen atom. As a result, the compound formed will not easily give up hydrogen atom upon dissociation.

Whereas less is the electronegativity of atom combining with hydrogen atom, easily it will donate the hydrogen atom upon dissociation.

Since, out of the given option sulfur (S) atom has low electronegativity as compared to oxygen and nitrogen atom.

Hence, $CH_{3}SH$ will easily donate hydrogen atom.

Thus, we can conclude that $CH_{3}SH$ molecule would be the best hydrogen bond donor.

4 0

3 years ago

Compounds can be separated by chemical means physical means boiling pressure

Gennadij [26K]

In order to compounds to be serparated, chemical means are needed. For example, if it you want to separate hydrogen and oxygen in the water ,an electric current should flow through it and that is a kind of chemical means(it is related to the chemical properties of the elements .)
While ,if there is a mixture ,it's components are rather separated easily in physical means. For instance, if you have a salt water, you are able to divide them by using each physical properties. Water is able to turn to a state of gas by evaporating or boiling. Using such properties, you could separate water from salt. Therefore, separating compounds and mixtures are all about the components physical or chemical properties.

So, the answer is a. I hope it will help you^^

6 0

3 years ago

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