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guapka [62]
3 years ago
11

Vitamin K is involved in normal blood clotting. When 0.802 g of vitamin K is dissolved in 25.0 g of camphor, the freezing point

of the solution is lowered by 2.69 °C. The freezing point and Kf constant for camphor can be found here. Calculate the molar mass of vitamin K.
Chemistry
1 answer:
xenn [34]3 years ago
7 0

Answer:

Molar mass of vitamin K = 450.56\frac{g}{mol}[/tex]

Explanation:

The freezing point of camphor = 178.4 ⁰C

the Kf of camphor =  37.7°C/m

where : m = molality

the relation between freezing point depression and molality is

Depression in freezing point = Kf X molality

Where

Kf = cryoscopic constant of camphor

molality = moles of solute dissolved per kg of solvent.

putting values

2.69°C = 37.7°C/m X molality

molality = 0.0714 mol /kg

molality=\frac{molesofvitaminK}{massofcamphor(kg)}=\frac{moles}{0.025}

moles of vitamin K = 0.0714X0.025 = 0.00178 mol

we know that moles are related to mass and molar mass of a substance as:

moles=\frac{mass}{molarmass}

For vitamin K the mass is given = 0.802 grams

therefore molar mass = \frac{mass}{moles}=\frac{0.802}{0.00178}=450.56\frac{g}{mol}

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RSB [31]
Reactivity trends of halogen:

1) Melting point and boiling points increased down the
group

2) Colour becomes darker.
E.g. Fluorine (pale yellow)
Chlorine (yellowish-green)
Bromine (reddish-brown)
Iodine (purplish-black)
Astatine (black)

3) The reactivity decreases down the group.
Reactivity:
F > Cl > Br > I > At
3 0
3 years ago
The teacher said the volume of the liquid was 500 mL when measured a student found it was 499.7 mL what is the students percent
Natalka [10]

Answer:

<h2>0.06 % </h2>

Explanation:

The percentage error of a certain measurement can be found by using the formula

P(\%) =  \frac{error}{actual \:  \: number}  \times 100\% \\

From the question

error = 500 - 499.7 = 0.3

actual volume = 500 mL

We have

p(\%) =  \frac{0.3}{500}  \times 100 \\  =  \frac{3}{50}  \\

We have the final answer as

<h3>0.06 % </h3>

Hope this helps you

4 0
3 years ago
Which element has the same number of valence electrons as calcium?
kipiarov [429]

Answer:

Barium has the same number of valence electrons as calcium

Explanation:

Valence electrons is the number of electrons of an atom on the outer shell.

Those valence electrons can participate in the formation of a chemical bond (if the outer shell is not closed); in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair.

<u>Calcium</u> is an atom, part of group 2, called the alkaline earth metals. The alkaline earth metals have 2 valence electrons.

<u>Sulfur </u>is part of a group 16, called the chalcogens or oxygen family. Those atoms have 6 valence electrons. They can form a bound with atoms of group 2 such as calcium, but do not have the same number of valence electrons.

<u>Potassium</u> is part of group 1, called the alkali metals or lithium family. Those atoms have 1 valence electrons. That means  Potassium do not have the same number of valence electrons like calcium.

<u>Neon</u> is part of group 18, the noble gasses. Those are stable atoms, which means they have 8 valence electrons. They do not have the same number of valence electrons like Calcium.

<u>Barium</u> an atom, part of group 2, called the alkaline earth metals. The alkaline earth metals have 2 valence electrons. Calcium is also part of this group.

This means barium has the same number of valence electrons as Calcium.

8 0
3 years ago
Element X is more reactive than lithium and magnesium but less reactive than potassium. Which element is most likely to be X?
PilotLPTM [1.2K]

Answer:

It is Likely to Be Sodium (Na) coz as You Down The group the reactivity increase

3 0
3 years ago
A cup of coffee has 71 mL of coffee and 127 mL of water. What is the percent volume of the coffee solution?
Anna [14]

Answer:

35.9%

Explanation:

The percent volume of the coffee solution can be calculated as follows:

% volume of coffee solution = volume of coffee/total volume of coffee solution × 100

According to this question, a cup of coffee has 71 mL of coffee and 127 mL of water. This means that, the total volume of coffee solution is;

71mL + 127mL = 198mL

% volume = 71/198 × 100

= 0.359 × 100

Percent volume of coffee solution = 35.9%

3 0
3 years ago
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