Photosynthesis is the process where plants create energy. It requires water, carbon dioxide and sunlight. The end result is glucose, which the plants consume, and oxygen. Cellular respiration requires oxygen and glucose. The end result is carbon dioxide, ATP, and water.

7 0

3 years ago

What is the Ka of a weak acid (HA) if the initial concentration of weak acid is 4.5 x 10-4 M and the pH is 6.87? (pick one)

rewona [7]

Answer:

Ka = $4.04 \times 10^{-11}$

Explanation:

Initial concentration of weak acid = $4.5 \times 10^{-4}\ M$

pH = 6.87

$pH = -log[H^+]$

$[H^+]=10^{-pH}$

$[H^+]=10^{-6.87}=1.35 \times 10^{-7}\ M$

HA dissociated as:

$HA \leftrightharpoons H^+ + A^{-}$

(0.00045 - x) x x

[HA] at equilibrium = (0.00045 - x) M

x = $1.35 \times 10^{-7}\ M$

$Ka = \frac{[H^+][A^{-}]}{[HA]}$

$Ka = \frac{(1.35 \times 10^{-7})^2}{0.00045 - 0.000000135}$

0.000000135 <<< 0.00045

$Therefore, Ka = \frac{(1.35 \times 10^{-7})^2}{0.00045 } = 4.04 \times 10^{-11}$

5 0

3 years ago

Which statement describes the relative energy of the electrons in the shells of a calcium atom?

Zina [86]

The answer is (3) An electron in the third shell has more energy than an electron in the second shell. The energy of electron will increase when number of shell increase.

7 0

3 years ago

Freezing point of carbon dioxide a.meter b.liter c.kilogram d.kelvin

Orlov [11]

The Freezing point is ALWAYS the same as the melting point,even for different elements. 6,422 is its melting,and freezing point. Same with gold,iron,hydrogen,and many others

7 0

3 years ago