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4 years ago

QUESTION 1

Chemistry

1 answer:

Scilla [17]4 years ago

7 0

Answer:

The answers are:

1) Latent heat of fusion

2) Heat is released

3) The process is endothermic

Explanation:

(1) The amount of energy required to freeze one kg of a substance is called latent heat of fusion.

(2) In a process, if heat is absorbed, the change in enthalpy for the substance is positive.

In a process, if heat is released, the change in enthalpy for the substance is negative.

The enthalpy of freezing for water is -6.02 kJ/mol. Heat is released as the enthalpy is negative.

(3) A positive value for enthalpy of vaporization indicates that the process is endothermic.

An exothermic process is one in which energy is released. The enthalpy for the process is negative.

An endothermic process is one which energy is absorbed. The enthalpy for the process is positive.

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You need to prepare 1 L of the citric acid/citrate buffer. You have chosen to use Method 1 (see lab presentation). Calculate the

prisoha [69]

Answer:

3.11 is the pH of the buffer

Explanation:

The pH of a buffer is obtained using H-H equation:

pH = pKa + log [Conjugate base] / [Weak acid]

<em>Where pH is the pH of the buffer, pKa = -log Ka = 3.14 for the citric buffer and [] could be taken as the moles of each species.</em>

The citric acid,HX (Weak acid), reacts with NaOH to produce sodium citrate, NaX (weak base) and water:

HX + NaOH → H2O + NaX

That means the moles of NaOH added = Moles of sodium citrate produced

And the resulitng moles of HX = Initial moles - Moles NaOH added

<em>Moles HX and NaX:</em>

Moles NaOH = 0.100L * (0.65mol / L) = 0.065 moles NaOH = Moles NaX

Moles HX = 0.300L * (0.45mol / L) = 0.135 moles HX - 0.065 moles NaOH = 0.070 moles HX

Replacing in H-H equation:

pH = 3.14 + log [0.065mol] / [0.070mol]

pH = 3.11 is the pH of the buffer

8 0

3 years ago

Acetic acid and ethanol react to form ethyl acetate and water, like this:

ladessa [460]

Answer:

1.) Option C is correct.

The rate of reverse reaction is greater than zero, but equal to the rate of the forward reaction.

2) Option B is correct.

The rate of reverse reaction is Greater than zero, but less than the rate of the forward reaction.

3) Option C is correct.

The rate of reverse reaction is Greater than zero, and equal to the rate of the forward reaction.

4) Option A is correct.

How much less C2H5CO2CH3 is in the flask when the system has again reached equilibrium? Zero.

Explanation:

HCH,CO2(aq) + C2H5OH(aq) ⇌ C2H,CO2CH3(aq) + H2O

1) Before the main product is removed from the reaction setup, the chemical reaction is at equilibrium.

Chemical equilibrium is a state of dynamic equilibrium such that the concentration of the reactants and the products do not always remain the same but the rate of forward reaction always matches the rate of backward reaction.

2) When 246. mmol of C2HCO2CH3 are removed from the reaction mixture....

And when one of the factors involved in chemical equilibrium changes, Le Chatellier's principle explains that the system then adjusts to remedy this change and takes time to go back to equilibrium again.

When one of the species involved in the chemical reaction at equilibrium, is removed from the reaction mixture, the rate of reaction begins to favour that side of the reaction until equilibrium is re-established.

So, when 246 mmol of one of the products is removed, the response is to cause the rate of forward reaction to be favoured to produce more of products as there are fewer, and the rate of reverse reaction at this moment becomes less than the rate of forward reaction.

3) The rate of the reverse reaction when the system has again reached equilibrium

Like I said in (2) above, the reaction remedies this change in concentration of one of the products until equilibrium is re-established and when chemical equilibrium is re-established the rate of forward reaction once again matches the rate of backward reaction.

4) How much less C2H5CO2CH3 is in the flask when the system has again reached equilibrium?

By the time equilibrium is re-established, the system goes back to how it all was and the concentration of C2H5CO2CH3 goes back to the same as it was at the start of the reaction.

Hope this Helps!!!

3 0

3 years ago

When dissolved sodium hydroxide reacts with hydrogen sulfate, aqueous sodium, sulfate, water, and heat are formed. Write out the

nignag [31]

Answer:

2 NaOH(aq) + H2SO4(aq) ⇒ Na2SO4 (aq) + 2 H2O(l)

Explanation:

4 0

3 years ago

A student sets up the following equation to convert a measurement. (The ? stands for a number the student is going to calculate.

kvasek [131]

Answer:

1 cm/s

Explanation:

From the question given above,

the student is trying to convert 0.010 m/s to a number in cm/s.

Thus, we can convert 0.010 m/s to cm/s as illustrated below:

Recall:

1 m/s = 100 cm/s

Therefore,

0.010 m/s = 0.010 m/s × 100 cm/s ÷ 1 m/s

0.010 m/s = 1 cm/s

Therefore, 0.010 m/s is equivalent to 1 cm/s

8 0

3 years ago

Burning alcohol for fuel is a very efficient process. Please select the best answer from the choices provided

Vedmedyk [2.9K]

Burning alcohol for fuel has been used throughout history. There are some alcohols that are the best ones to use as fuels because of their nature and can be synthesized chemicaly or biologicaly. Except, some of those alcohol also has a bad effect when burned for fuel as it would cause serious negative chemical effects when exposed to the human body such as blindness or death. Therefore, the best answer would be False.

6 0

4 years ago

Read 2 more answers