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2 years ago

What do the COEFFICIENTS in a chemical reaction represent?

1 answer:

3 0

Answer:First: the coefficients give the number of molecules (or atoms) involved in the reaction. In the example reaction, two molecules of hydrogen react with one molecule of oxygen and produce two molecules of water. Second: the coefficients give the number of moles of each substance involved in the reaction.

Explanation: PLESE GIVE BRAINLIEST

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An atom of element X has one more shell of electrons than an atom of beryllium, but it has one less valance electron than beryll

irakobra [83]

The atomic number of Be is 4, and so it has 2 shells. There are valence electrons in the second, which is the outermost, shell of Be. To get the element with one more shell, there would be 3 shells on the new element, and 1 less valence electron, so the new element should have 1 valence electron. Sodium is the element with 3 shells, and one valence electron which fits perfectly into the description.

3 0

2 years ago

Calculate the enthalpy of the reaction

harkovskaia [24]

Answer : The enthalpy of the reaction is, -2552 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 given enthalpy of reaction is,

$4B(s)+3O_2(g)\rightarrow 2B_2O_3(s)$ $\Delta H=?$

The intermediate balanced chemical reactions are:

(1) $B_2O_3(s)+3H_2O(g)\rightarrow 3O_2(g)+B_2H_6(g)$ $\Delta H_A=+2035kJ$

(2) $2B(s)+3H_2(g)\rightarrow B_2H_6(g)$ $\Delta H_B=+36kJ$

(3) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l)$ $\Delta H_C=-285kJ$

(4) $H_2O(l)\rightarrow H_2O(g)$ $\Delta H_D=+44kJ$

Now we have to revere the reactions 1 and multiple by 2, revere the reactions 3, 4 and multiple by 2 and multiply the reaction 2 by 2 and then adding all the equations, we get :

(when we are reversing the reaction then the sign of the enthalpy change will be change.)

The expression for enthalpy of the reaction will be,

$\Delta H=-2\times \Delta H_A+2\times \Delta H_B-6\times \Delta H_C-6\times \Delta H_D$

$\Delta H=-2(+2035kJ)+2(+36kJ)-6(-285kJ)-6(+44)$

$\Delta H=-2552kJ$

Therefore, the enthalpy of the reaction is, -2552 kJ/mole

4 0

2 years ago

How many electrons does carbon need to gain to obtain a noble gas electron configuration

laila [671]

Carbon has 4 valence electrons so to gain a noble gas electron configuration, which has 8 valence electrons and is the most electrically stable, carbon needs 4 more electrons.

4 0

2 years ago

25.2 mL of water are placed in a graduated cylinder. A 22.6 g stone is dropped in, and the water level rises to 32.4 mL. Find th

VMariaS [17]

<span>Displaced volume :

final volume - initial volume

32.4 mL - 25.2 mL => 7.2 mL

Density = mass / volume

D = 22.6 g / 7.2 mL

D = 3.1388 g/mL

hope this helps!</span>

5 0

2 years ago

ХА

kvasek [131]

Answer:

B. Biosphere.

Explanation:

8 0

2 years ago