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3 years ago

Explain the difference between a theory and scientific law

2 answers:

8 0

Theory- <span>a supposition or a system of ideas intended to explain something, especially one based on general principles independent of the thing to be explained.

Scientific law- </span>a statement based on repeated experimental observations that describes some aspect of the universe.

Burka [1]3 years ago

3 0

A scientific theory is an in depth explanation of a observed phenomena And scientific law is simply an observation of the phenomenon that the theory attempts to explain. like when newton saw an apple fall form a tree he observed a phenomena which is called the law of gravity the law states that every time you drop an apple it will fall to the ground and the theory would explan why the apple falls to the ground.

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If a sample of air in a closed container was heated, would the total pressure of the air in the container increase, decrease, or

telo118 [61]

Answer: Stay the same

Explanation:

Boyle's law is one of the fundamental gas laws, that describes the state of an ideal gas at a constant temperature. It states that the volume of a gas is inversely proportional to the external pressure applied at a constant temperature.

5 0

3 years ago

Is Italian salad dressing a pure substance or a mixture ?

Evgen [1.6K]

Answer:mixture

Explanation:

4 0

4 years ago

alculate the standard enthalpy of formation of ethanoic acid given that the standard enthalpy of combustion for carbon is –394 k

agasfer [191]

Answer:

The standard enthalpy of formation of ethanoic acid is -484 kJ/mol.

Explanation:

$C(g)+O_2(g)\rightarrow CO_2(g),\Delta H_{1, comb}=-394 kJ/mol$ ...[1]

$H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l),\Delta H_{2, comb}=-286 kJ/mol$ ..[2]

$CH_3COOH(l)+2O_2(g)\rightarrow 2CO_2(g)+2H_2O(l),\Delta H_{3, comb}=-876 kJ/mol$ ..[3]

The standard enthalpy of formation of ethanoic acid :

$2C(g)+2H_2(g)+O_2(g)\rightarrow CH_3COOH, \Delta H_{4}=?$ ..[4]

Using Hess's law to calculate :

2 × [1] + 2 × [2] - [3] = [4]

$\Delta H_4=2\times (-394 kJ/mol)+2\times (-286 kJ/mol) - (-876 kJ/mol)$

$=\Delta H_4=-484 kJ/mol$

The standard enthalpy of formation of ethanoic acid is -484 kJ/mol.

5 0

3 years ago

What quantity of copper is deposited by the same quantity of electricity that deposited 9g of aluminum

klio [65]

Answer:

Mass of copper deposited = 31.75 g

Explanation:

According to Faraday's second law of electrolysis, when the same quantity of electricity is passed through different electrolytes, the relative number of moles of the elements deposited are inversely proportional to the charges on the ions of the elements.

From this law, it can be seen that the higher the charge, the lower the number of moles of a given element deposited.

Number of moles of aluminium in 9 g of aluminium = mass / molar mass

Molar mass of aluminium = 27 g

Number of moles of aluminium = 9/27 = 1/3 moles

Charge on aluminium ion = +3

3 moles of electrons will discharge 1 mole of aluminium,

1 mole of electrons will discharge 1/3 moles of aluminium

Number of moles of electrons involved = 1 mole of electrons

Charge on copper ion = +2

1 mole of electrons will discharge 1/2 moles of copper.

Mass of 1/2 moles of copper = number of moles × molar mass of copper

Molar mass of copper = 63.5 g

Mass of copper deposited = 1/2 × 63.5 = 31.75 g

3 0

3 years ago

If a 0.2g of oil consumed 1ml of sodium thiosulphate, calculate its iodine value and classify the oil?

marta [7]

Iodine value is a measure of the degree of unsaturation in fats and oils. It is essentially the number of grams of iodine consumed by 100 g of fat. If the iodine number is in the range of 0-70 then it is a fat, any value above 70 is considered an oil.

Formula:

Iodine number = (ml of 0.1 N Thiosulphate blank- ml of 0.1N thiosulphate test) * 12.7 *100/1000* wt of sample

vol of thiosulphate required to titrate test sample (given oil) = 1 ml

wt of sample = 0.2 g

Information on the volume of thiosulphate required to titrate the blank solution is essential for calculation.

Iodine number = (X-1.0) * 12.7 * 100/1000* 0.2 = (X-1.0)*6.35

6 0

4 years ago