What is the chemical formula of this organic compound

CH3COOH  CH3COO– + H+

Oxana [17]

(a)

pH = 4.77

; (b)

[

H

3

O

+

]

=

1.00

×

10

-4

l

mol/dm

3

; (c)

[

A

-

]

=

0.16 mol⋅dm

-3

Explanation:

(a) pH of aspirin solution

Let's write the chemical equation as

m

l

HA

m

+

m

H

2

O

⇌

H

3

O

+

m

+

m

l

A

-

I/mol⋅dm

-3

:

m

0.05

m

l

0

m

l

0

C/mol⋅dm

-3

:

m

l

-

x

m

+

x

m

l

m

l

+

x

E/mol⋅dm

-3

:

m

0.05 -

l

x

m

l

x

m

x

m

x

K

a

=

[

H

3

O

+

]

[

A

-

]

[

HA

]

=

x

2

0.05 -

l

x

=

3.27

×

10

-4

Check for negligibility

0.05

3.27

×

10

-4

=

153

<

400

∴

x

is not less than 5 % of the initial concentration of

[

HA

]

.

We cannot ignore it in comparison with 0.05, so we must solve a quadratic.

Then

x

2

0.05

−

x

=

3.27

×

10

-4

x

2

=

3.27

×

10

-4

(

0.05

−

x

)

=

1.635

×

10

-5

−

3.27

×

10

-4

x

2

+

3.27

×

10

-4

x

−

1.635

×

10

-5

=

0

x

=

1.68

×

10

-5

[

H

3

O

+

]

=

x

l

mol/L

=

1.68

×

10

-5

l

mol/L

pH

=

-log

[

H

3

O

+

]

=

-log

(

1.68

×

10

-5

)

=

4.77

(b)

[

H

3

O

+

]

at pH 4

[

H

3

O

+

]

=

10

-pH

l

mol/L

=

1.00

×

10

-4

l

mol/L

(c) Concentration of

A

-

in the buffer

We can now use the Henderson-Hasselbalch equation to calculate the

[

A

-

]

.

pH

=

p

K

a

+

log

(

[

A

-

]

[

HA

]

)

4.00

=

−

log

(

3.27

×

10

-4

)

+

log

(

[

A

-

]

0.05

)

=

3.49

+

log

(

[

A

-

]

0.05

)

log

(

[

A

-

]

0.05

)

=

4.00 - 3.49

=

0.51

[

A

-

]

0.05

=

10

0.51

=

3.24

[

A

-

]

=

0.05

×

3.24

=

0.16

The concentration of

A

-

in the buffer is 0.16 mol/L.

hope this helps :)

6 0

2 years ago

I have trouble figuring out these questions help!!

Zina [86]

1. Density=mass/volume=2kg/6m=0.33kg/m (convert to proper units)
2. Density=mass/volume=0.6kg/3L=0.2kg/L (convert to proper units)
3. Density=mass/volume= 129g / 30 cm (convert to proper units)
V=length*width*height=2*3*5 = 30
4. Volume (units) = cm^3 because, like in problem 3, Volume=width(cm)*length(cm)*height(cm)
However, when you pour liquid into a cylinder (so the volume would be the liquid), you measure it in mL.
5. Volume with rock - initial volume (without the rock) = Volume of rock
18.2-12.7= 5.5

3 0

3 years ago

Which balanced equation represents a redox reaction? a. AgNO3(aq) +NaCl(aq) →AgCl(s) +NaNO3(aq) b. H2CO3(aq) →H2O() + CO2(g) c.

Aleks [24]

Answer : The correct option is, (D) $Mg(s)+2HCl(aq)\rightarrow MgCl_2(s)+H_2(g)$

Explanation :

(A) $AgNO_3(aq)+NaCl(aq)\rightarrow AgCl(s)+NaNO_3(aq)$

This reaction is a double displacement reaction in which the cation and anion of two reactants are exchange their places to give two different products.

(B) $H_2CO_3(aq)\rightarrow H_2O(l)+CO_2(g)$

This reaction is a decomposition reaction in which the larger molecule decomposes to give two or more products.

(C) $NaOH(aq)+HCl(aq)\rightarrow NaCl(s)+H_2O(aq)$

This reaction is a neutralization reaction in which an acid and a base react to give a salt and water as a product.

(D) $Mg(s)+2HCl(aq)\rightarrow MgCl_2(s)+H_2(g)$

This reaction is a redox reaction in which the oxidation and reduction reaction occur simultaneously.

Oxidation reaction is the reaction in which a substance looses its electrons. In this oxidation state increases.

Reduction reaction is the reaction in which a substance gains electrons. In this oxidation state decreases.

In this reaction, magnesium shows oxidation due to change in oxidation number from (0) to (+2) and hydrogen shows reduction due to change in oxidation number from (-1) to (0).

Hence, the correct option is, (D)

7 0

3 years ago

Really need help with the rest of them, please it's due in 20 minutes

ArbitrLikvidat [17]

Answer:

chlorine is for pool

Explanation:

hope is help

8 0

3 years ago

How many grams of carbon dioxide are produced from the combustion of 250.G of ethane, C3H8 in the reaction C3H8 +5O2 - 3CO2 +4H2

ludmilkaskok [199]

Answer:

750 g of CO₂

Explanation:

The balanced equation for the reaction is given below:

C₃H₈ + 5O₂ —> 3CO₂ + 4H₂O

Next, we shall determine the mass of C₃H₈ that reacted and the mass of CO₂ produced from the balanced equation. This can be obtained as follow:

Molar mass of C₃H₈ = (12×3) + (8×1)

= 36 + 8 = 44 g/mol

Mass of C₃H₈ from the balanced equation = 1 × 44 = 44 g

Molar mass of CO₂ = 12 + (16×2)

= 12 + 32 = 44 g/mol

Mass of CO₂ = 3 × 44 = 132 g

SUMMARY:

From the balanced equation above,

44 g of C₃H₈ reacted to produce 132 g of CO₂.

Finally, we shall determine the mass of CO₂ produced by the reaction of 250 g of C₃H₈. This can be obtained as follow:

From the balanced equation above,

44 g of C₃H₈ reacted to produce 132 g of CO₂.

Therefore, 250 g of C₃H₈ will react to produce = (250 × 132)/44 = 750 g of CO₂.

Thus, 750 g of CO₂ were obtained from the reaction.

8 0

2 years ago