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Anna71 [15]
3 years ago
5

A scientist is studying a chemical reaction. She predicts that after the reaction the product will have less chemical potential

energy than the reactants had originally. The scientist observes the reaction, and notes that no light or sound is produced. However, other observations support the scientist's prediction that the total chemical potential energy has decreased. DESCRIBE one observation that would support her prediction.
Chemistry
1 answer:
Ymorist [56]3 years ago
4 0

The reaction becomes warmer or hotter as it proceeds. This means that touching the container in which the reaction is taking place would feel hotter. This means the reaction dissipates heat energy and has a negative enthalpy. The reaction is written with  a negative delta- H in the products side for the reaction to be balanced.

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A formic acid buffer solution contains 0. 20 m h c o o h hcooh and 0. 24 m h c o o − hcoox−. the pka of formic acid is 3. 75. wh
irina1246 [14]

A buffer solution contains an equivalent amount of acid and base. The pH of the solution with an acid dissociation constant (pKa) value of 3.75 is 3.82.

<h3>What is pH?</h3>

The amount of hydrogen or the proton ion in the solution is expressed by the pH. It is given by the sum of pKa and the log of the concentration of acid and bases.

Given,

Concentration of salt [HCOO⁻] = 0.24 M

Concentration of acid [HCOOH] = 0.20 M

The acid dissociation constant (pKa) = 3.75

pH is calculated from the Hendersons equation as,

pH = pKa + log [salt] ÷ [acid]

pH = 3.75 + log [0.24] ÷ [0.20]

= 3.75 + log (1.2)

= 3.75 + 0.079

= 3.82

Therefore, 3.82 is the pH of the buffer.

Learn more about pH here:

brainly.com/question/27181245

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6 0
2 years ago
Identify from the following list of molecules and ions which behave as Lewis acids: CO2, NH3, BCl3, Fe3+. (A) CO2 and NH3 (B) NH
Anettt [7]

Answer : The correct option is, (D) CO₂, BCl₃, and Fe³⁺

Explanation :

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

(a) CO_2

It is a Lewis-acid because it can accepts electron pairs.

(b) NH_3

It is not a Lewis-acid because it can not accepts electron pairs but it is a base because it can donates and accept hydrogen ion.

(c) BCl_3

It is a Lewis-acid because it can accepts electron pairs because it has an incomplete octet and an empty 2p orbital.

(d) Fe^{3+}

It is a Lewis-acid because it can accepts electron pairs.

Hence, the ions which behave as Lewis acids are, CO₂, BCl₃, and Fe³⁺

6 0
3 years ago
When elemental iron corrodes it combines with oxygen in the air to ultimately form red brown iron(iii) oxide which we call rust.
iren [92.7K]
<span>The mass of the nail would increase, because the iron is adding oxygen to its chemical composition. This would increase the overall mass. If the mass increases from 23.2g to 24.1g, then the increase would be the difference between the two masses, or 0.9g.</span>
7 0
4 years ago
A standard gold bar has a mass of 12.4 kg. When the gold bar is placed into a container of water the volume changes by 642 mL. W
AlekseyPX

Answer:

19.3 g/mL

Explanation:

The following data were obtained from the question:

Mass (m) = 12.4 kg

Volume (V) = 642 mL.

Density (D) =.?

Next, we shall convert 12.4 kg to grams. This can be obtained as follow:

1 kg = 1000 g

Therefore,

12.4 kg = 12.4 × 1000

12.4 kg = 12400 g

Therefore, 12.4 kg is equivalent to 12400 g.

Finally, we shall determine the density of the gold as follow:

Density is simply defined as the mass of the substance per unit volume of the substance. It can be represented mathematically as:

Density (D) = mass (m) / volume (V)

D = m/V

With the above formula, the density of gold can easily be obtained as follow:

Mass (m) = 12400 g

Volume (V) = 642 mL.

Density (D) =.?

D = m/V

D = 12400/642

D = 19.3 g/mL

Therefore, the density of hold is 19.3 g/mL

6 0
3 years ago
Which subatomic particle of an atom never changes?
AlexFokin [52]
Protons are one of the fully stable parts of matter
8 0
4 years ago
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