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3 years ago

Why is frying an egg an example of a chemical change?

1 answer:

6 0

In chemistry, a chemical change is a change which involves the production of new chemical substances. Frying an egg is an example of a chemical change because of the reaction between the oil and the substance in the presence of supplied heat.

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PLEASE HELP, WILL MARK BRAINLIEST!!!!! TIME IS RUNNING OUT!!!!

faltersainse [42]

This is a redox reaction where oxidation and a reduction occur.

Here, Mg goes to Mg²⁺ by changing its oxidation number from 0 to +2 while S goes to S²⁻ by reducing its oxidation state from 0 to -2 . Hence Mg is oxidized by S in the reaction.

Reducing agent is a substance which reduces other substance by oxidizing itself. Hence, the reducing agent of this reaction is Magnesium.

6 0

3 years ago

Technetium has a half-life of six hours. If you obtain 100g of a pure technetium sample, after 18 hours how much of the pure sub

IgorLugansk [536]

Answer:

After 18 hours, the amount of pure technetium that will be remaining is 12.5 grams

Explanation:

To solve the question, we note that the equation for half life is as follows;

$N(t) = N_0 (\frac{1}{2} )^{\frac{t}{t_{1/2}}$

Where:

N(t) = Quantity of the remaining substance = Required quantity

N₀ = Initial radioactive substance quantity = 100 g

t = Time duration = 18 hours

${t_{1/2}$ = Half life of the radioactive substance = 6 hours

Therefore, plugging in the values, we have;

$N(t) = 100 (\frac{1}{2} )^{\frac{18}{6}} = 100 (\frac{1}{2} )^{3} = \frac{100 }{8} = 12.5 \ grams$

Therefore, after 18 hours, the amount of pure technetium that will be remaining = 12.5 grams.

6 0

3 years ago

Define valence electrons.

vodka [1.7K]

Answer:

Electrons on the outermost shell of an atom. They are responsible for the chemical properties of an atom.

8 0

3 years ago

Which scientist performed the cathode ray experiment leading to the discovery of electrons?

Drupady [299]

My answer -

The scientist that performed the cathode ray experiment leading to the discovery of electrons is the scientist Sir Joseph John Thompson or J.J. Thompson. It was theorized after the discovery that electrons are present in the atom. In this model, the atom is composed mainly of electrons. It was describe as plum pudding because the electrons are dispersed within the atom.

P.S

Happy to help you have an AWESOME!!! day ^-^

3 0

3 years ago

A 2.00-mol sample of hydrogen gas is heated at constant pressure from 294 K to 414 K. (a) Calculate the energy transferred to th

Furkat [3]

Answer:

a) The energy transferred is 6.91 kJ

b) The internal energy is 4.90 kJ

c) The work done on the gas is - 2.01 kJ

Explanation:

Step 1: Data given

Number of moles of hydrogen gas = 2.00 moles

Pressure = constant

Temperature is heated from 294 K to 414 K

Molar heat capacity of hydrogen gas = 28.8 J/mol*K

Step 2: Calculate the energy transferred to the gas by heat.

Q = n* Cp * ΔT

⇒with Q =the energy transferred

⇒with n = the number of moles = 2.00 moles

⇒with Cp = the Molar heat capacity of hydrogen gas = 28.8 J/mol*K

⇒ with ΔT = Temperature 2 - Temperature 1 = 414 - 294 = 120K

Q = 2.00 * 28.8 * 120

Q = 6912 J = 6.91 kJ

Step 3: Calculate the increase in its internal energy.

ΔEint = n*Cv*ΔT

⇒with ΔEint = the increase in its internal energy.

⇒with n = the number of moles = 2.00 moles

⇒with Cv = The constant volume = 20.4 J/mol*K

⇒with ΔT = Temperature 2 - Temperature 1 = 414 - 294 = 120K

ΔEint = 2.00 * 20.4 * 120

ΔEint =4896 J = 4.90 kJ

Step 4: Calculate the work done on the gas.

Work done on the gas = -Q + ΔEint

W = -6.91 kJ + 4.90 kJ

W = -2.01 kJ

6 0

3 years ago