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ANEK [815]
3 years ago
14

Why are red blood cells red

Chemistry
1 answer:
KonstantinChe [14]3 years ago
8 0

Red blood cells are red because they contain Haemoglobin

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Which two practices are examples of how people use science?
Anika [276]

B. Developing theories using many lines of evidence

4 0
3 years ago
Read 2 more answers
Which phase change results in atoms with the highest kinetic energy? A. Boiling B. Melting C. Freezing D. Condensing
suter [353]

Answer: Boiling because it makes the molecules in water bounce around.

Hope it helps.

4 0
2 years ago
A phosphate buffer is involved in the formation of urine. The developing urine contains H2PO4 and HPO42- in the same concentrati
Katen [24]

Answer:

The ionization equation is

H_{2}PO_{4}^{-}  +H_{2}O ⇄HPO_{4}^{-2}  +H_{3}O^{+} (1)

Explanation:

The ionization equation is

H_{2}PO_{4}^{-}  +H_{2}O ⇄HPO_{4}^{-2}  +H_{3}O^{+} (1)

As the Bronsted definition sais, an acid is a substance with the ability to give protons thus, H2PO4 is the acid and HPO42- is the conjugate base.

The Ka expression is the ratio between the concentration of products and reactants of the equilibrium reaction so,

Ka = \frac{[HPO_{4}^{-2}] [H_{3}O^{+}]}{[H_{2}PO_{4}^{-}] [H_{2}O]} = 6.2x10^{-8}

The pKa is

-Log (Ka) = -Log (6.2x10^{-8}) = 7.2

The pKa of H2CO3 is 6,35, thus this a stronger acid than H2PO4. The higher the pKa of an acid greater the capacity to donate protons.

In the body H2CO3 is a more optimal buffer for regulating pH due to the combination of the two acid-base equilibriums and the two pKa.

If the urine is acidified, according to Le Chatlier's Principle the equilibrium (1)  moves to the left neutralizing the excess proton concentration.

3 0
3 years ago
The combustion of 0.1240 kg of propane in the presence of excess oxygen produces 0.3110 kg of carbon dioxide. What is the limiti
nadezda [96]

Answer:

The limiting reactant is the propane gas, C₃H₈ while the percentage yield is 83.77%

Explanation:

Here we have

Propane gas with molecular formula C₃H₈, molar mass  = 44.1 g/mol combining with O₂ as follows

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Therefore, 1 mole of C₃H₈  combines with 5 moles of O₂ to produce 3 moles CO₂ and 4 moles of H₂O

Mass of propane = 0.1240 kg = 124.0 g

Number of moles of propane = mass of propane/(molar mass of propane)

The number of moles of propane = 124/44.1 = 2.812 moles

The molar mass of CO₂ = 44.01 g/mol

Mass of CO₂ = 0.3110 kg = 311.0 g

Therefore, number of moles of CO₂ = mass of CO₂/(molar mass of CO₂)

The number of moles of CO₂ = 311.0 kg/ 44.01 g/mol = 7.067 moles

Therefore, since 1 mole of propane produces 3 moles of CO₂, 2.812 moles of propane will produce 3 × 2.812 moles or 8.44 moles of CO₂

Therefore;

The limiting reactant is the propane gas, C₃H₈, since the oxygen is in excess

Hence

The \ percentage \ yield = \frac{Actual \, yield}{Theoretical \, yield} \times 100 = \frac{7.067}{8.44} \times 100 = 83.77 \%

The percentage yield = 83.77%.

7 0
3 years ago
At standard pressure, the difference between the freezing point and the boiling point of water, in Kelvin degrees, is D. 373 A.
Sergio [31]
The answer to this question is A. 100
 

7 0
2 years ago
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