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3 years ago

Activity A moles need hlp

Chemistry

1 answer:

damaskus [11]3 years ago

7 0

I would always start by balancing your carbons, and then balancing the rest from there.

1. C2H5OH + O2 —> CO2 + H2O - You have two carbons on the left and one on the right. Multiply CO2 by 2.
C2H5OH + O2 —> 2CO2 + H2O

Now balance hydrogen. You have 6 on the left and 2 on the right. Multiply H2O by 3.
C2H5OH + O2 —> 2CO2 + 3H2O

Now balance oxygen. You have 3 on the left and 7 on the right. You need 4 more on the left. Don’t multiply the C2H5OH by anything because that will change the numbers of everything else too. Multiply O2 by 3 instead.
C2H5OH + 3O2 —> 2CO2 + 3H2O

Check that all atoms are now balanced, and you’re good.

2. Same process as before.

First carbons - C3H8 + O2 —> 3CO2 + H2O
Then hydrogens - C3H8 + O2 —> 3CO2 + 4H2O
Then oxygens - C3H8 + 5O2 —> 3CO2 + 4H2O

3. Same again.

Carbons) C6H12O6 + O2 —> 6CO2 + H2O
Hydrogens) C6H12O6 + O2 —> 6CO2 + 6H2O
Oxygens) C6H12O6 + 6O2 —> 6CO2 + 6H2O

4. The general reaction for a combustion reaction is a hydrocarbon reacting with oxygen to produce carbon dioxide and water.

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Calculate [H3O+] and [OH−] for each of the following solutions at 25 ∘C given the pH.<br> pH= 2.89

dimaraw [331]

Answer: The value of $[H_{3}O^{+}]$ is 0.0012 M and $[OH^{-}]$ is $1.02 \times 10^{-14}$ .

Explanation:

pH is the negative logarithm of concentration of hydrogen ion.

It is given that pH is 2.89. So, the value of concentration of hydrogen ions is calculated as follows.

$pH = - log [H^{+}]\\2.89 = - log [H^{+}]\\conc. H^{+} = 0.0012 M$

The relation between pH and pOH value is as follows.

pH + pOH = 14

0.0012 + pOH = 14

pOH = 14 - 0.0012 = 13.99

Now, pOH is the negative logarithm of concentration of hydroxide ions.

Hence, $[OH^{-}]$ is calculated as follows.

$pOH = - log [OH^{-}]\\13.99 = - log [OH^{-}]\\conc. OH^{-} = 1.02 \times 10^{-14} M$

Thus, we can conclude that the value of $[H_{3}O^{+}]$ is 0.0012 M and $[OH^{-}]$ is $1.02 \times 10^{-14}$ .

6 0

3 years ago

you do a calculation on a molecule and determined that the energy of the highest occupied molecular orbital (homo) is -2.42 hart

UkoKoshka [18]

The wavelength of the photon required to excite this molecule from its ground state, to its first excited state is 1240 nm.

This is given by the equation:

wavelength = hc/(E_homo - E_lumo)

where h is Planck's constant =6.626070 * 10^-34 J.m , c is the speed of light = 3.0 x 10^8 m/s^2, and E_homo and E_lumo are the energies of the highest occupied molecular orbital and the lowest unoccupied molecular orbital, respectively.

In this particular case, the wavelength of the required photon would be:

wavelength = hc/(-2.42 hartree - 0.65 hartree)

= 6.626070 * 10^-34 X 3.0 x 10^8 / (-3.07)

= 1240 nm

Hence , The wavelength of the photon required to excite this molecule from its ground state, to its first excited state is 1240 nm.

Learn more about wavelength at : brainly.com/question/13533093

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4 0

1 year ago

If you have 2 of the same substance and they are at the same temperature but have a different amount, what changes?

Lina20 [59]

Answer:

The heat energy stored within them changes

Explanation:

Heat energy is a function of the mass of a body, its specific heat capacity, and its temperature.

In this case, the bodies have the same specific heat capacity since they are made from the same material and the same temperature.

To get the quantity of heat stored in a body, we need to multiply all three parameters as shown below

$Q = mC \Delta T$

An increase in mass, through an increase in the amount of substance of a material present, will cause a corresponding increase in the heat energy stored within the material

6 0

3 years ago

The wax in a burning candle can be described by both physical and chemical properties. What are the physical properties of the w

dimaraw [331]

Answer:

The change of state of wax from solid to liquid and liquid to vapors is a physical change.

Explanation:

Physical Change

The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.

These changes were reversible.

They have same chemical property.

These changes can be observed with naked eye.

Chemical:

The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.

These changes are irreversible .

These changes occur due to chemical reactions.

These may not be observed with naked eye

Example

When a candle is burned, the both physical and chemical changes occur.

The solid wax is melted into the liquid and than liquid is evaporated into vapor form. It is a physical change because just the state of mater is changed. When vapors of wax are react with oxygen in air and form carbon dioxide and ash it is a chemical change which can not be reversed.

8 0

3 years ago

prease tell me the answer. When a liquid changes to a gas below the surface of a liquid as well as at the surface, it is called

Anton [14]

Its called freezing, the change from a liquid to a gas is called vaporization

6 0

4 years ago

Read 2 more answers