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Maksim231197 [3]
2 years ago
9

ХА

Chemistry
1 answer:
kvasek [131]2 years ago
8 0

Answer:

B. Biosphere.

Explanation:

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Why do we use scientific notation or scientific exponential numbers in math calculations?
seraphim [82]
I believe the answer is: in order not to write very big or very small number values
6 0
3 years ago
A 100.00 ml of volume of 0.500 M HCl was mixed with 100.00 ml of 0.500 M KOH in a constant pressure calorimeter. The initial tem
Virty [35]

Answer:

The heat of the reaction = -1985 J = -1.985 kJ

The enthalpy of the reaction is -39.7 kJ/ mol

Explanation:

<u>Step 1: </u>Data given

Volume of HCl = 100 mL the heat of the reaction = 0.1 L

Molarity of HCl solution = 0.500 M

Volume of KOH = 100 mL = 0.1 L

Molarity of KOH solution = 0.500 M

Initial temperature = 23.0 °C

Final temperature = 25.5 °C

Specific heat of the solution = 3.97 J/°C *g

Density of the solution = 1g/ mL

<u>Step 2: </u>Calculate heat

Q = m*c*ΔT

with m = the mass of both solution : 100g + 100 g ( since density = 1g/mL) = 200 g

c = the specific heat = 3.97 J/°C*g

ΔT  = T2 -T1 = 25.5 = 23 = 2.5 °C

Q = 200g *3.97 J/°C*g * 2.5°C = 1985 J  (= -1985 J because it's exothermic)

<u />

<u>Step 3:</u> Calculate the number of moles

Number of moles = Molarity * Volume

Number of moles = 0.5 * 0.1 L = 0.05 moles

(Moles of the acid are equal to the moles of water produced.

Moles of solution = 0.05 moles)

<u>Step 4: </u>Calculate the enthalpy of the reaction

ΔH = heat change /Number of moles

    = -1.985 kJ/ 0.05 moles

   =- 39700 J/mol = -39.7 kJ/ mol

The enthalpy of the reaction is -39.7 kJ/ mol

The enthalpy of the reaction is negative, this means the reaction is exothermic ( which means the final temperature is higher than the initial temperature.)

7 0
3 years ago
Hydrogen peroxide can be prepared by the reaction of barium peroxide with sulfuric acid according to the reaction BaO2(s)+H2SO4(
Vesna [10]

Answer:

VH2SO4 = 145.3 mL

Explanation:

Mw BaO2 = 169.33 g/mol

⇒ mol BaO2 = 53.5g * ( mol BaO2 / 169.33 g BaO2) = 0.545 mol BaO2

⇒according to the reaction:

mol BaO2 = mol H2SO4 = 0.545 mol

⇒ V H2SO4 = 0.545 mol H2SO4 * ( L H2SO4 / 3.75 mol H2SO4 )

⇒V H2SO4 = 0.1453 L (145.3 mL)

6 0
2 years ago
Read 2 more answers
In the compound cah2 calcium has an oxidation number of 2+ and hydrogen has an oxidation number of
sesenic [268]

The oxidation number of H is -1.

Sum of the oxidation numbers in each element = charge of the complex

CaH₂ has 1 Ca atom and 2H atoms. The charge of the complex is zero. Let’s say Oxidation number of H is "a".

Then,

<span>    (+2) + 2 x a = 0 </span>

<span>        +2  + 2a  = 0</span>

                  2a = -2

                    a = -1

Hence, the oxidation number of Hydrogen atom in CaH₂ is -1


7 0
2 years ago
Please help now!!! 20 braily points!!!
Zigmanuir [339]

Hydrogen atom and chlorine atom makes hydrogen chloride molecules.

It is the lowest point in the substance and possesses chemical elements. Atoms don't exist on their own; instead, they combine to create ions and molecules, which combine to create the substances that we can see, feel, and touch.

One or more atoms joined together by covalent (chemical) connections make up molecules. Atoms can be imagined as circles with a central nucleus (consisting of protons and neutrons) and one or more concentric circles surrounding it that represent the "shells" or "levels" in which the electrons surrounding the atom's nucleus are located as well as markings that distinguish the electron. every level

To know more about  molecules visit : brainly.com/question/11405437

#SPJ1

4 0
1 year ago
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