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guapka [62]
2 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]2 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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Explanation:

the description of the procedure ensures that when the experiment  becomes of a success,specific steps are recorded for improvement of the experiment if maybe the experiment can be done at a short space of time.

3 0
3 years ago
Help me please!!!!!!!!!!!!!!!
Alex787 [66]

Answer:

2KBr + MgF₂ –> 2KF + MgBr₂

The coefficients are: 2, 1, 2, 1

Explanation:

KBr + MgF₂ –> KF + MgBr₂

The above equation can be balance as illustrated below:

KBr + MgF₂ –> KF + MgBr₂

There are 2 atoms of F on the left side and 1 atom on the right. It can be balance by writing 2 before KF as shown below:

KBr + MgF₂ –> 2KF + MgBr₂

There 2 atoms of K on the right side and 1 atom on the left side. It can be balance by writing 2 before KBr as shown below:

2KBr + MgF₂ –> 2KF + MgBr₂

Now, the equation is balanced.

The coefficients are: 2, 1, 2, 1

8 0
2 years ago
Determine the kinetic energy of an 833.0 kg roller coaster car moving at a speed of 20.0 m/s
trasher [3.6K]

Answer:

166,600J

Explanation:

Kinetic energy (K.E), which is the energy due to motion of a body, can be calculated by using the formula;

K.E = 1/2 × m × v²

Where;

K.E = kinetic energy (joules)

m = mass of body (kg)

v = speed or velocity (m/s)

According to this question, the mass of the roller coaster is 833.0 kg while its velocity/speed is 20.0m/s.

K.E = 1/2 × 833 × 20²

K.E = 1/2 × 833 × 400

K.E = 1/2 × 333200

K.E = 166,600

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2 years ago
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asambeis [7]

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Thus, statement (1), (3) and (4) is correct whereas statement (2) and (5) is incorrect.

7 0
3 years ago
Read 2 more answers
Calculate the volume of 5.0 grams of NO gas at STP.
Sveta_85 [38]

Answer:

The volume of  5.0 g CO  2  is  2.6 L CO  2  at STP

Explanation:

STP

STP is currently  

0

∘

C

or  

273.15 K

, which are equal, though the Kelvin temperature scale is used for gas laws; and pressure is  

10

5

.

Pascals (Pa)

, but most people use  

100 kPa

, which is equal to  

10

5

.

Pa

.

You will use the ideal gas law to answer this question. Its formula is:

P

V

=

n

R

T

,

where  

P

is pressure,  

V

is volume,  

n

is moles,  

R

is a gas constant, and  

T

is temperature in Kelvins.

Determine moles

You may have noticed that the equation requires moles  

(

n

)

, but you have been given the mass of  

CO

2

. To determine moles, you multiply the given mass by the inverse of the molar mass of  

CO

2

, which is  

44.009 g/mol

.

5.0

g CO

2

×

1

mol CO

2

44.009

g CO

2

=

0.1136 mol CO

2

Organize your data

.

Given/Known

P

=

100 kPa

n

=

0.1136 mol

R

=

8.3145 L kPa K

−

1

mol

−

1

https://en.wikipedia.org/wiki/Gas_constant

T

=

273.15 K

Unknown:  

V

Solve for volume using the ideal gas law.

Rearrange the formula to isolate  

V

. Insert your data into the equation and solve.

V

=

n

R

T

P

V

=

0.1136

mol

×

8.3145

.

L

kPa

K

−

1

mol

−

1

×

273.15

K

100

kPa

=

2.6 L CO

2

rounded to two significant figures due to  

5.0 g

Answer link

Doc048

May 18, 2017

I got 2.55 Liters

Explanation:

1 mole of any gas at STP = 22.4 Liters

5

g

C

O

2

(

g

)

=

5

g

44

(

g

mole

)

=

0.114

mole

C

O

2

(

g

)

Volume of 0.114 mole  

C

O

2

(

g

)

= (0.114 mole)(22.4 L/mole) = 2.55 Liters  

C

O

2

(g) at STP

6 0
3 years ago
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