Help this is for ap ex help me please

Dafna11 [192]

Energy is invisible yet it's all around us and throughout the universe. Energy can never be made or destroyed, but its form can be converted and changed.
While energy can be transferred or transformed, the total amount of energy does not change – this is called energy conservation.
Energy transformation, also known as energy conversion, is the process of changing energy from one form to another. In physics, energy is a quantity that provides the capacity to perform work or provides heat.
When energy is transformed from one form to another, or moved from one place to another, or from one system to another there is energy loss. This means that when energy is converted to a different form, some of the input energy is turned into a highly disordered form of energy, like heat. This consent is known as “hidden energy”.

4 0

3 years ago

I need help with both questions

a_sh-v [17]

Answer:

not sure about 6 but 7 should be c

Explanation:

..

6 0

3 years ago

Which of the following you is true for a limiting reactant

skad [1K]

Answer:

C) The limiting reactant has the lowest ratio of moles available / coefficient in the balanced equation.

Explanation:

Please, find attached a complete question to determine which of the statements is or are true for a limiting reactant in a chemical equation.

First, remember that the limiting reactant is the substance that is consumed completely while the excess reactant is the substance that does not react completely.

The limiting reactant is found comparing the stoichiometry ratio and the actual ratio between the reactants.

The stoichiometry ratio is found using the coefficientes of the chemical equation.

For illustration, assume the general chemical equation:

$aA+bB\rightarrow cC+dD$

The stoichiometric ratio of the reactants is:

$a\text{ }moles\text{ }of\text{ }A/b\text{ }moles\text{ }of\text{ }B$

If the ratio of the available moles of substance A to the available moles of substance B is greater than the stoichiometric ratio, it means that there are more moles of the substance A than what is needed to react with the available moles of substance B, then A will be in excess and B will B the limiting reactant.

If, on the contrary, the ratio of the available moles of substance A to the available moles of substance B is is less than the stoichiometric ratio, then substance A is less than the necessary to make the all the moles of substance B react, meaning that the substance A will limit the reaction (it will be consumed completely), while the substance B will be in excess.

As for the options:

A) The limiting reactant is has the lowest coefficient in a balanced equation.

This is false, since it is not the magnitude of the coefficiente what determines the limiting reactant, but the comparison of the ratios.

B) The limiting reactant is the reactant for which you have the fewest number of moles.

This is false because it is not the number of moles what determines the limiting reactant , but the comparison of the ratios.

C) The limiting reactant has the lowest ratio of moles available / coefficient in the balanced equation.

This is true as proved below.

The stoichiometric ratio of the reactants is:

$a\text{ }moles\text{ }of\text{ }A/b\text{ }moles\text{ }of\text{ }B$

The actual ratio is:

$available\text{ }moles\text{ }of\text{ }A/available\text{ }moles\text{ }of\text{ }B$

Assume the first ratio is less than the second (which describes when the substance A is in excess and the limiting reactant is the substance B).

$a\text{ }moles\text{ }of\text{ }A/b\text{ }moles\text{ }of\text{ }B$

Change the relation to show the ratios of moles available of each substance to the cofficient in the chemical equation:

$available\text{ }moles\text{ }of\text{ }B/b\text{ }moles\text{ }of\text{ }B$

Then, in the scenary that the limiting reactant is the substance B, the ratio of the left is lower than the ratio of the right, which is the same that limiting reactant has the lowest ratio of moles available / coefficient in the balanced equation.

D) The limiting reactant has the lowest ratio of coefficients in the balanced eqution/moles available.

This ratio is the inverse of the ratio of the previous statement, thus the relation is inverse, and, since the previous statement was true, this statement is false.

3 0

2 years ago

At STP, a sample of gas occupies 0.225 L. Calculate the volume of this gas at a pressure of 2.7 atm and a temperature of 320 K.

irinina [24]

Answer:

This new temperature is 97.7 mL

Explanation:

Step 1: Data given

Volume = 0.225 L

STP = 1 atm and 273 K

Pressure = 2.7 atm

Temperature = 320 K

Step 2: Calculate new volume

(P1*V1)/T1 = (P2*V2)/T2

⇒with P1 = the pressure at STP = 1 atm

⇒with V1 = the volume = 0.225 L

⇒with T1 = the temperature at STP = 273 K

⇒with P2 = the new pressure = 2.7 atm

⇒with V2 = the new volume = TO BE DETERMINED

⇒with T2 = the new temperature = 320 K

(1atm *0.225 L)/273 K = (2.7 atm * V2) /320 K

8.24 * 10^-4 = 2.7 * V2 / 320K

2.7V2 = 0.264

V2 = 0.0977 L = 97.7 mL

This new temperature is 97.7 mL

8 0

3 years ago

Calculate the vapor pressure of a solution of 0.99 mol of cholesterol in 5.4 mol of toluene at 32°c. pure toluene has a vapor pr

blondinia [14]

We can get the vapor pressure of the solution from this formula:
Pv(solu) = n P°v
when n is the mole fraction of toluene so we can get by substitution in this formula:
n = moles of toluene / (moles of cholesterol + moles of toluene)
= 5.4 / ( 0.99 + 5.4) = 0.85
so by substitution in vapor pressure formula:
∴ Pv(solu) = 0.85 *41 = 34.85 atm

4 0

3 years ago

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