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Evgesh-ka [11]
3 years ago
8

How much heat, in calories, is needed to raise the temperature of 125.0 g of Lead (c lead = 0.130 J/g°C) from 17.5°C to 41.1°C?

Chemistry
1 answer:
pav-90 [236]3 years ago
8 0
95.6 cal
are needed.
Explanation:
Use the following equation:
q
=
m
c
Δ
T
,
where:
q
is heat energy,
m
is mass,
c
is specific heat capacity, and
Δ
T
is the change in temperature.
Δ
T
=
T
final
−
T
initial
Known
m
=
125 g
c
Pb
=
0.130
J
g
⋅
∘
C
T
initial
=
17.5
∘
C
T
final
=
42.1
∘
C
Δ
T
=
42.1
∘
C
−
17.5
∘
C
=
24.6
∘
C
Unknown
q
Solution
Plug the known values into the equation and solve.
q
=
(
125
g
)
×
(
0.130
J
g
⋅
∘
C
)
×
(
24.6
∘
C
)
=
400. J

(rounded to three significant figures)
Convert Joules to calories
1 J
=
0.2389 cal
to four significant figures.
400
.
J
×
0.2389
cal
1
J
=
95.6 cal

(rounded to three significant figures)
95.6 cal
are needed.
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Identify the acid, base, conjugate acid and conjugate base in the following reactions:
Leni [432]

Answer:

a. NH₃ : base

CH₃COOH (acetic acid) : acid

NH₄⁺ : conjugate acid

CH₃COO⁻ : conjugate base

b. HClO₄ (perchloric acid) : acid

NH₃ : base

ClO₄⁻ : conjugate base

NH₄⁺ : conjugate acid

Hope this helps.

4 0
3 years ago
Why carbon monoxide is not acidic ​
mojhsa [17]

Answer:

Well, carbon monoxide can be created from formic acid by adding sulphuric acid which will dehydrate said formic acid:

HCOOH

−

→

−

−

−

H

2

SO

4

CO+H

2

O

HCOOH→HX2SOX4CO+HX2O

Therefore, we can imagine the reverse reaction theoretically, which would make carbon monoxide an acidic oxide. However, the forward reaction does not proceed easily and it needs both the high acidity of sulphuric acid and its strong dehydrative properties to actually work. And your question mentions using hot, concentrated sodium hydroxide to make the reverse one work.

Most oxides that are classified as acidic or basic either have a very electrophilic central atom (e.g.  

CO

2

COX2

) which can be attacked by the weak nucleophile water (which in turn can then release an acidic proton), or they have a high charge density on the oxygen which allows it to abstract a proton from water directly. Carbon monoxide is neither. If you check out its molecular orbitals, you will notice that even though carbon is partially positive it has the largest HOMO contribution, meaning a proton would be more likely to attatch to the carbon side — which doesn’t want one at all. The LUMO is, luckily, also more carbon-centred, meaning nucleophilic attacks on carbon are possible. However, it is also degenerate due to the double bond so that an attack is not favoured.

Thus, the carbon monoxide molecule is one that won’t react with water at all and totally defies the concept of acidic/basic oxides.

Abbreviations:

HOMO is a widely used abbreviation for the Highest Occupied Molecular Orbital, i.e. the one with the highest energy that still contains electrons. It is usually the orbital that will attack nucleophilicly or that will be attacked electrophilicly.

LUMO is a widely used abbreviation for the Lowest Unoccupied Molecular Orbital, i.e. the virtual (unoccupied) orbital that has the lowest energy. When considering a nucleophilic attack, the attacking electrons will usually interact with the LUMO. Electrophiles attack with other molecules’ HOMO with their LUMO.

Explanation:

7 0
3 years ago
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sineoko [7]
The cruise control on a car is an example of a control loop.
3 0
3 years ago
The air pressure for a certain tire is 113 KPa. What is the pressure I’m atmosphere
Fynjy0 [20]

Answer: 1.11 atm

Explanation:

The unit of pressure include kilopascal (kPa), atmospheres (atm), mmHg etc

Now, given that:

Air pressure = 113 KPa

Convert kPa to atm

If 101.325 kPa = 1 atm

113 kPa = Z atm

To get the value of Z, cross multiply

Z atm x 101.325 kPa = 1 atm x 113 kPa

Z = ( 1 atm x 113 kPa) / 101.325 kPa

Z = 1.11 atm

Thus, the pressure is 1.11 atm

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Chemical equations are used to model
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Answer:

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