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Sever21 [200]
3 years ago
5

What did people use for energy before fossil fuel and electrical power energy was harnessed?

Chemistry
1 answer:
8_murik_8 [283]3 years ago
5 0

Before the occurance of Fossil fuel, our energy needs were modest. For heat, we relied on the sun—and burned wood, straw, and dried dung For transportation, the muscle of horses and the power of the wind in our sails took us to every corner of the world.

<h3>What is Fossil Fuel ?</h3>

Fossil fuels are made from decomposing plants and animals.

These fuels are found in the Earth's crust and contain carbon and hydrogen, which can be burned for energy.

Coal, oil, and natural gas are examples of fossil fuels.

Hence, Before the occurance of Fossil fuel, our energy needs were modest. For heat, we relied on the sun—and burned wood, straw, and dried dung For transportation, the muscle of horses and the power of the wind in our sails took us to every corner of the world.

Learn more about Fossil fuel here ;

brainly.com/question/2029072

#SPJ1

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In an experiment temperature and the amount of NaCI dissolved in water were studied researchers changed the temperature of the w
Evgesh-ka [11]

Answer:

Dependent variable: Amount of NaCI dissolved in water

Explanation:

In an experiment, the DEPENDENT VARIABLE is the variable that the experimenter measures. It is the variable whose response is dependent on the independent variable.

In this experiment, researchers were studying the temperature and the amount of NaCI dissolved in water i.e. how a change in temperature affected the amount of NaCl dissolved. They conducted two tests one changing the temperature (experimental group) and another without changing the temperature (control group) the temperature change. It is clear that the RESPONDING/DEPENDENT VARIABLE IN THIS EXPERIMENT IS THE AMOUNT OF NACL DISSOLVED.

3 0
3 years ago
What is the mass of 4.50 moles of magnesium chloride, MgCl2?
Vedmedyk [2.9K]

Answer:

427.5g

Explanation:

Given parameters:

Number of moles  = 4.5moles

Unknown:

Mass of MgCl₂  = ?

Solution:

To solve this problem;

     Mass  = number of moles x molar mass

Molar mass of MgCl₂  = 24 + 2(35.5) = 95g/mol

  Mass  = 4.5 x 95  = 427.5g

7 0
3 years ago
If a temperature increase from 21.0 ∘c to 35.0 ∘c triples the rate constant for a reaction, what is the value of the activation
Airida [17]

Answer:

59.077 kJ/mol.

Explanation:

  • From Arrhenius law: <em>K = Ae(-Ea/RT)</em>

where, K is the rate constant of the reaction.

A is the Arrhenius factor.

Ea is the activation energy.

R is the general gas constant.

T is the temperature.

  • At different temperatures:

<em>ln(k₂/k₁) = Ea/R [(T₂-T₁)/(T₁T₂)]</em>

k₂ = 3k₁ , Ea = ??? J/mol, R = 8.314 J/mol.K, T₁ = 294.0 K, T₂ = 308.0 K.

ln(3k₁/k₁) = (Ea / 8.314 J/mol.K) [(308.0 K - 294.0 K) / (294.0 K x 308.0 K)]

∴ ln(3) = 1.859 x 10⁻⁵ Ea

∴ Ea = ln(3) / (1.859 x 10⁻⁵) = 59.077 kJ/mol.

4 0
3 years ago
(The radioisotope 224Ra decays by alpha emission via two paths to the ground state of its daughter 94% probability of alpha deca
pav-90 [236]

Answer:

a) ²²⁴Ra₈₈ ---> α + ²²⁰Rn₈₆ + Q

b) the Q-value of this reaction is 5.789 MeV

c) the energies (in MeV) of the two associated alpha particles are; 5.69 MeV and 5.449 Mev

       

Explanation:

a)

The decay equation for the alpha decay is expressed as;

²²⁴Ra₈₈ ---> α + ²²⁰Rn₈₆ + Q

b)

Calculate the Q-value (in MeV) of this reaction.

Q = Mparent - Mdaughter -Mg

Q = MRa - MRn -Mg

= 224.020202 - 220.011384 - 4.00260305

= 0.00621495 amu

= 5.789 MeV

therefore the Q-value of this reaction is 5.789 MeV

c)

Energy of alpha particle is expressed as;

E∝ = MQ / ( m + M)

now this is the maximum energy available for the daughter, ²²⁰Rn going to the ground state;

The energy of the alpha particle gives;

E∝  = 220(5.789) / ( 4 + 220) = 5.69 MeV

as given in the question,The other less frequent alpha occurring 5.5% of the time leaves the daughter nucleus in an excited state of 0.241 MeV above the ground state.

Therefore the energy of this alpha is

E∝ = 5.69 - 0.241 = 5.449 Mev

Therefore the energies (in MeV) of the two associated alpha particles are; 5.69 MeV and 5.449 Mev

d)

Sketch of the nuclear decay scheme have been uploaded along side this answer.

7 0
4 years ago
A gas is collected at 20.0 °C and 725.0 mm Hg. When the temperature is
krek1111 [17]

Answer:

676mmHg

Explanation:

Using the formula;

P1/T1 = P2/T2

Where;

P1 = initial pressure (mmHg)

P2 = final pressure (mmHg)

T1 = initial temperature (K)

T2 = final temperature (K)

According to the information provided in this question;

P1 = 725.0mmHg

P2 = ?

T1 = 20°C = 20 + 273 = 293K

T2 = 0°C = 0 + 273 = 273K

Using P1/T1 = P2/T2

725/293 = P2/273

Cross multiply

725 × 273 = 293 × P2

197925 = 293P2

P2 = 197925 ÷ 293

P2 = 676mmHg.

The resulting pressure is 676mmHg

3 0
3 years ago
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