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Luda [366]
3 years ago
6

What is the percent composition of carbon in caffeine (C₈H₁₀N₄O₂)?

Chemistry
1 answer:
podryga [215]3 years ago
5 0

Caffeine has the following percent composition: carbon 49.48%, hydrogen 5.19%, oxygen 16.48% and nitrogen 28.85%. Its molecular weight is 194.19 g/mol.

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A buffer solution contains 0.345 M acetic acid and 0.377 M sodium acetate . If 0.0613 moles of potassium hydroxide are added to
melamori03 [73]

Answer:

pH = 5.54

Explanation:

The pH of a buffer solution is given by the <em>Henderson-Hasselbach (H-H) equation</em>:

  • pH = pKa + log\frac{[CH_3COO^-]}{[CH_3COOH]}

For acetic acid, pKa = 4.75.

We <u>calculate the original number of moles for acetic acid and acetate</u>, using the <em>given concentrations and volume</em>:

  • CH₃COO⁻ ⇒ 0.377 M * 0.250 L = 0.0942 mol CH₃COO⁻
  • CH₃COOH ⇒ 0.345 M * 0.250 L = 0.0862 mol CH₃COOH

The number of CH₃COO⁻ moles will increase with the added moles of KOH while the number of CH₃COOH moles will decrease by the same amount.

Now we use the H-H equation to <u>calculate the new pH</u>, by using the <em>new concentrations</em>:

  • pH = 4.75 + log\frac{(0.0942+0.0613)mol/0.250L}{(0.0862-0.0613)mol/0.250L} = 5.54
6 0
3 years ago
35. In the collision theory, a collision that leads to the formation of products is called an
FinnZ [79.3K]

Answer:

It's Effective Collision.

Explanation:

Hope my answer has helped you!

7 0
3 years ago
A solution of sodium hydroxide (NaOH) was standardized against potassium hydrogen phthalate (KHP). A known mass of KHP was titra
Eddi Din [679]

Answer:

See explanation below

Explanation:

In order to calculate this, we need to use the following expression to get the concentration of the base:

MaVa = MbVb (1)

We already know the volume of NaOH used which is 13.4473 mL. We do not have the concentration of KHP, but we can use the moles. We have the mass of KHP which is 0.5053 g and the molecular formula. Let's calculate the molecular mass of KHP:

Atomic weights of the elements to be used:

K = 39.0983 g/mol;  H = 1.0078 g/mol;  C = 12.0107 g/mol;  O = 15.999 g/mol

MM KHP = (1.0078*5) + (39.0983) + (8*12.0107) + (4*15.999) = 204.2189 g/mol

Now, let's calculate the mole of KHP:

moles = 0.5053 / 204.2189 = 0.00247 moles

With the moles, we also know that:

n = M*V (2)

Replacing in (1):

n = MbVb

Now, solving for Mb:

Mb = n/Vb  (3)

Finally, replacing the data:

Mb = 0.00247 / (13.4473/1000)

Mb = 0.184 M

This would be the concentration of NaOH

8 0
3 years ago
How many joules of heat is lost when a 64 g piece of copper cools from 375 oC to 26 oC? The specific heat of copper is 0.38 J/go
Svetlanka [38]

Answer: 8500 J lost or -8500 J

Explanation:

q=cmt

t=375-26

t=349

q=0.38(64)(349)

q=8487.68 J

Answer must have 2 sig figs, which means it rounds to 8500 J.

7 0
3 years ago
What are the units used to measure specific heat capacity?
Andrews [41]

The units used to measure specific heat capacity is Joules per kilogram per Kelvin.

<h3>What is specific heat capacity?</h3>

It is the amount of heat absorbed per kilogram of material when the temperature rises by 1 Kelvin.

Specific heat capacity C is the Joules of energy in form of heat per kilogram per Kelvin temperature. The units represented by

C = ___ J/kg.K

Thus, the units used to measure specific heat capacity is Joules per kilogram per Kelvin.

Learn more about specific heat capacity.

brainly.com/question/1747943

#SPJ4

7 0
2 years ago
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