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3 years ago

A prehistoric pharmacist might have been called a

Chemistry

1 answer:

Shkiper50 [21]3 years ago

5 0

A. Shaman

Shaman were revered as people with the ability to communicate with good and evil spirits and heal ailments.

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Stearic acid (C18H36O2) is a fatty acid, a molecule with a long hydrocarbon chain and an organic acid group (COOH) at the end. I

Paha777 [63]

Answer:

There is 9671 Kj of heat released

Explanation:

Step 1: The balanced equation:

C18H36O2(s) + 26O2(g) --> 18CO2(g)+18H2O(g)

This means for 1 mole of C18H36O2 consumed there is 26 moles of O2 needed to produce 18 moles of CO2 and 18 moles of H2O.

Step 2: Calculate the heat of combustion

ΔH (combustion) = [18*(ΔHf of CO2) + 18*(ΔHf of H2O)] - [1*(ΔHf of C18H36O2) + 26*(ΔHf of O2)]

ΔH (combustion) = [18*(-394 kJ/mol) + 18*(-242 kJ/mol)] - [1*(-948 kJ/mol) + 26*(0 kJ/mol)]

ΔH (combustion) = [(-7092 kJ/mol) + (-4356 kJ/mol)] - (-948 kJ/mol)

= -10500 kJ/mol

ΔH (combustion) = heat released / number of moles of stearic acid

Step 3: Calculate moles of stearic acid

moles of stearic acid = mass / Molar mass of stearic acid

moles of stearic acid = 262g / 284.48 g/mole = 0.921 moles

Step 4: Calculate moles of oxygen

moles of O2 = 914.5 / 32g/mole

moles of O2 = 28.578125 moles

Stearic acid is the limiting reactant: it will completely react

There will react 26*0.921 mole = 23.946 mole of O2

This means there will remain 4.63 moles of O2

Step 5: Calculate heat released

q = (ΔH combustion) * (moles of stearic acid) = (-10500 kJ/mol) * (0.921 moles) = 9671 Kj

There is 9671 Kj of heat released

6 0

3 years ago

What energy is stored

denis-greek [22]

Answer: potential energy is stored

Explanation:

3 0

3 years ago

Why is it important to have the correct bond angles of the different atoms and the shape of the molecule? (20 points NEED ANSWER

hjlf

It is important to have the correct bond angles of the different atoms and the shape of the molecule due to following reasons;

Among other properties the polarity of compounds mainly depend upon the shape and bond angles of that particular compound. For example, considering the molecule of water, we already know that it is a polar molecule with partially positive hydrogen atoms and partially negative oxygen atoms and acts as universal solvent. The bond angle in water is about 104.5° with a Bent geometry. Unlike carbon dioxide (CO₂) which has Linear structure with bond angle 180° and is non-polar in nature therefore, the bent geometry in water is responsible for the polarity.

Other properties which can also be predicted by predicting the bond angles along with molecular geometries are;

i) Magnetism

ii) Phase of matter

iii) Color

iv) Reactivity

v) Biological activities e.t.c

5 0

3 years ago

When heated, calcium carbonate goes through a chemical reaction, and produces calcium oxide (quick lime) powder and carbon

Contact [7]

Answer:

Carbon dioxide is produced, and as a gas, it was not captured to measure its mass.

Explanation:

4 0

4 years ago

Read 2 more answers

An ionic bond is best described as

LekaFEV [45]

The answer would be B the transfer of electrons from one atom to another

6 0

4 years ago

Read 2 more answers