The law that states that heat flows from warmer to colder objects is the..

Calculate the percentage of copper in copper oxide

WITCHER [35]

Well, look up the atomic weights of copper and oxygen; add them appropriately; divide the total for the copper by the total for the molecule; then multiply by 100 to get it as a percentage.

5 0

3 years ago

Why do you think there was a rush to mass-produce penicillin around the time of World War II?

Vladimir79 [104]

Answer:

penicillin could protect mice against infection from deadly Streptococci.

Explanation:

5 0

3 years ago

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An element belonging to the halogen family would be expected to have a ________ ionization energy and a ________ electron affini

nikklg [1K]

An element belonging to the halogen family would be expected to have a large ionization energy and a large electron affinity.
Flourine, Chlorine, Bromine, Iodine and astatine are the elements that belongs to the halogen family and mostly they have high values of ionization energy.
The amount of energy released when an electron is added to an atom or molecule to form a negative ion or anion is electron affinity.Chlorine from this family has highest electron affinity.

8 0

3 years ago

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

Calculate the mass percent (m/m) of a solution prepared by dissolving 51.56 g of NaCl in 164.2 g of H2O. Express your answer to

denis-greek [22]

Answer:

"23.896%" is the right answer.

Explanation:

The given values are:

Mass of NaCl,

= 51.56 g

Mass of H₂O,

= 165.6 g

As we know,

⇒ Mass of solution = $Mass \ of \ (NaCl+H_2O)$

= $51.56+164.2$

= $215.76 \ g$

hence,

⇒ $Mass \ percent =\frac{Mass \ of \ NaCl}{Mass \ of \ solution}\times 100$

$=\frac{51.56}{215.76}\times 100$

$=23.896 \ percent$

4 0

3 years ago