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telo118 [61]
3 years ago
9

The calcium content of urine can be determined by the following procedure: Ca2+ is precipitated as calcium oxalate in basic solu

tion: Ca2+(aq) + C2O4 2(aq)  Ca(C2O4)H2O(s) After the precipitate is washed with ice-cold water to remove free oxalate, the solid is dissolved in acid, which gives Ca2+ and H2C2O4 in solution. The dissolved oxalic acid is heated to 60C and titrated with standardized potassium permanganate, KMnO4, until the purple end point is reached. 5 C2O4 2(aq) + 2 MnO4 (aq) + 16 H+(aq)  10 CO2(g) + 2 Mn2+(aq) + 8 H2O(l) (colorless) (purple) (colorless) Titration of 0.1978 g of Na2C2O4 (FW: 134.00 g/mol) required 38.65 mL of a standard permanganate, MnO4 , solution. The calcium in a 25.00 mL urine sample was precipitated by the procedure above, redissolved and required 41.35 mL of the standard MnO4  solution. What is the concentration of Ca2+ in the urine in units of mg /dL?
Chemistry
1 answer:
crimeas [40]3 years ago
8 0

Answer:

25317 mg/dL

Explanation:

Based in the reaction:

5 C₂O₄²⁻(aq) + 2 MnO4⁻(aq) + 16 H⁺(aq) → 10 CO₂(g) + 2 Mn²⁺(aq) + 8H₂O(l)

5 moles of oxalate react with 2 moles of permanganate.

The concentration of the KMnO₄ is:

0,1978g Na₂C₂O₄ ₓ (1mol / 134,00g) × (2mol permangante/ 5 mol oxalate) / 0,03865L = <em>0,01528M KMnO₄</em>

In the precipitation of Calcium, you can see moles of oxalate ≡ moles of Ca. Thus:

Moles of titrated oxalate:

0,04135L × (0,01528moles / L)× (5moles oxalate / 2 moles permanganate) = 1,579x10⁻³ moles of oxalate≡ moles of Ca²⁺.

1,579x10⁻³ moles Ca ₓ (40,078g / mol) = 0,06329g Ca / 25,00mL = 2,532x10⁻³g/mL.

In mg/dL =

2,532x10⁻³ g/mL ₓ (1000mg /g) ₓ (10000mL / 1dL) = <em>25317 mg/dL</em>

I hope it helps!

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what is the number of pairs of electrons that are shared between the nitrogen atoms in a molecule of N2
lesantik [10]
A Nitrogen got 7 electrons, which means every Nitrogen got 3 pairs of electrons and 1 single electron, ready to be shared.
A second nitrogen come with the same amount of electrons, 3 pairs and 1 single ready to shared. 
The 2 nitrogens put in common their single electrons to create a pair. 
Which means, that 1 pair of electron is shared between the nitrogens in a molecule of N2

Hope this Helps! :)
3 0
3 years ago
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What kind of air mass will bring cold, dry weather as it moves toward an area
sergij07 [2.7K]

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i think the answer is Continental polar air masses

Explanation:

4 0
2 years ago
The half-life of tritium (H-3) is 12.3 years. If 48.0mg of tritium is released from a nuclear power plant during the course of a
Rudiy27

Answer:

The amount left after 49.2 years is 3mg.

Explanation:

Given data:

Half life of tritium = 12.3 years

Total mass pf tritium = 48.0 mg

Mass remain after 49.2 years = ?

Solution:

First of all we will calculate the number of half lives.

Number of half lives = T elapsed/ half life

Number of half lives =  49.2 years /12.3 years

Number of half lives =  4

Now we will calculate the amount left after 49.2 years.

At time zero 48.0 mg

At first half life = 48.0mg/2 = 24 mg

At second half life = 24mg/2 = 12 mg

At 3rd half life = 12 mg/2 = 6 mg

At 4th half life =  6mg/2 = 3mg

The amount left after 49.2 years is 3mg.

6 0
3 years ago
A binding protein binds to a ligand l with a kd of 400 nm what is the concentration of ligand when y is 0.25
vampirchik [111]

Answer:

The answer is 7600 nm.

Explanation:

As, Y = 0.25 = [ L ÷ (400 + (L)]

0.95 x 400 + 0.25 [ L] = [ L ]

380.25  = [ L ] - 0.95 [ L ]

              = 0.05 [L]

[L] = 380 ÷ 0.05 = 7600nm

6 0
3 years ago
4) What volume will the gas in the balloon at right occupy at 250k?<br><br> balloon: 4.3L 350K
swat32

Answer:

2.87 liter.

Explanation:

Given:

Initially volume of balloon = 4.3 liter

Initially temperature of balloon = 350 K

Question asked:

What volume will the gas in the balloon occupy at 250 K ?

Solution:

By using:

Pv =nRT

Assuming pressure as constant,

V∝ T

Now, let  K is the constant.

V = KT

Let initial volume of balloon , V_{1} = 4.3 liter

1000 liter = 1 meter cube

1 liter = \frac{1}{1000} m^{3} = 10^{-3} m^{3

4.3 liter = 4.3\times10^{-3}=4.3\times10^{-3} m^{3}

And initial temperature of balloon, T_{1} = 350 K

Let the final volume of balloon is V_{2}

And as given, final temperature of balloon, T_{2} is 250 K

Now, V_{1} = KT_{1}

4.3\times10^{-3}=K\times350\ (equation\ 1 )

V_{2} = KT_{2}

=K\times250\ (equation 2)

Dividing equation 1 and 2,

\frac{4.3\times10^{-3}}{V_{2} } =\frac{K\times350}{K\times250}

K cancelled by K.

By cross multiplication:

350V_{2} =4.3\times10^{-3} \times250\\V_{2} =\frac{ 4.3\times10^{-3} \times250\\}{350} \\          = \frac{1075\times10^{-3}}{350} \\          =2.87\times10^{-3}m^{3}

Now, convert it into liter with the help of calculation done above,

2.87\times10^{-3} \times1000\\2.87\times10^{-3} \times10^{3} \\2.87\ liter

Therefore, volume of the gas in the balloon at 250 K will be  2.87 liter.

4 0
3 years ago
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