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Marina86 [1]
2 years ago
15

I NEED HELP WITH 1-4 PLEASE ASAP!!!

Chemistry
1 answer:
Varvara68 [4.7K]2 years ago
5 0

Answer:

1 is the same    3 is pure substance 4 is different

Explanation:

not sure about 2

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Ice cream is made by freezing a liquid mixture that, as a first approximation, can be considered a solution of sucrose in water.
hjlf

Answer:

Freezing point is -2.81°C

Explanation:

34g/342gmol^-1 = 0.0994mol

n = m/mr

Molarity= 0.994/ 0.66 = 1.51M

◇T = -i × m ×Kf

Where ◇T is freezing depression

i= Vant Hoff factor

m = molarity

Kf = freezing content = 1.

860kgmol^-1

◇T =-1 × 1.51 × 1.860 = - 2.81°C

6 0
3 years ago
If you have access to stock solutions of 1.00 M H3PO4, 1.00 M of HCl, and 1.00 M NaOH solution, (and distilled water of course),
garri49 [273]

Answer:

0.10L of 1.00M of H₃PO₄ and 0.1613L of 1.00M NaOH

Explanation:

The pKa's of phosphoric acid are:

H₃PO₄/H₂PO₄⁻ = 2.1

H₂PO₄⁻/HPO₄²⁻ = 7.2

HPO₄²⁻/PO₄³⁻ = 12.0

To make a buffer with pH 9.40 we need to convert all H₃PO₄ to H₂PO₄⁻ and an amount of H₂PO₄⁻ to HPO₄²⁻

To have a 50mM solution of phosphoures we need:

2L * (0.050mol / L) = 0.10 moles of H₃PO₄

0.10 mol * (1L / mol) = 0.10L of 1.00M of H3PO4

To convert the H₃PO₄ to H₂PO₄⁻ and to HPO₄²⁻ must be added NaOH, thus:

H₃PO₄ + NaOH → H₂PO₄⁻ + H₂O + Na⁺

H₂PO₄⁻ + NaOH → HPO₄²⁻ + H₂O + Na⁺

Using H-H equation we can find the amount of NaOH added:

pH = pKa + log [A⁻] / [HA] <em>(1)</em>

<em>Where [A-] is conjugate base, HPO₄²⁻ and [HA] is weak acid, H₂PO₄⁻</em>

<em>pH = 7.40</em>

<em>pKa = 7.20</em>

[A-] + [HA] = 0.10moles <em>(2)</em>

Replacing (2) in (1):

7.40 = 7.20 + log 0.10mol - [HA] / [HA]

0.2 = log 0.10mol - [HA] / [HA]

1.5849 = 0.10mol - [HA] / [HA]

1.5849 [HA] = 0.10mol - [HA]

2.5849[HA] = 0.10mol

[HA] = 0.0387 moles = H₂PO₄⁻ moles

That means moles of HPO₄²⁻ are 0.10mol - 0.0387moles = 0.0613 moles

The moles of NaOH needed to convert all H₃PO₄ in H₂PO₄⁻ are 0.10 moles

And moles needed to obtain 0.0613 moles of HPO₄²⁻ are 0.0613 moles

Total moles of NaOH are 0.1613moles * (1L / 1mol) = 0.1613L of 1.00M NaOH

Then, you need to dilute both solutions to 2.00L with distilled water.

4 0
2 years ago
What is the only planet in our solar system that rotates in a different direction from the other planets??​
aksik [14]
Venus so that the sun rises in the west
4 0
3 years ago
NEED HELP WITH THIS CHEMISTRY QUESTION
denis-greek [22]

Answer:

1341541345134514355143

Explanation:

THIS DUMB B~!TCH  GAVE ME THIS ANSWER

8 0
2 years ago
Layer B in the diagram is located between the crust and core in terms of location, temperature, and pressure. What part of the e
nignag [31]
The answer is c) the mantle


8 0
3 years ago
Read 2 more answers
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