Experiment 39 Algae plant photolytic intensity determination

experiment 39 algae photolytic intensity determinationprinciple Algae plants in photocodesic absorption of CO
2
, release oxygen. By measuring the oxygen content of the water in the algae container, the photolyceric intensity of the algae plants can be calculated.to measure dissolved oxygen in water using Winkler's method, which is accurate and simple. Even polar spectrometry needs to be calibrated with this method.this method is based on the addition of manganese dioxide (MnCl
2
) and sodium hydroxide to the quantitative water, both of which react to produce manganese hydroxide (Mn (OH)
2
). If there is oxygen in the water, Mn (OH)
2
can be oxidized to Mn (OH)
3
. With potassium iodide and hydrochloric acid, Mn (OH)
3
to MnCl
3
. MnCl
3
reaction with KI, freeing iodine, and its weight is related to oxygen in water.4MnCl
2
8NaOH→4Mn (OH)
2
8NaCl 4Mn (OH)
2
O
A2
2H
2
O→4Mn (OH)
3 4Mn (OH)
3
12HCl→4MnCl
3
12H
2
O 4MnCl
3
4KI→4MnCl
2
2I
2
KClthe above reaction as a total chemical reaction type: 8NaOH 12HCl 4KI O
2
→8NaCl 10H
2
O 4KCl 2I
2
(1)Iodine with sodium sulfate titration, Na
2
S
2
O
3
and I
2
between the molar relationship;2I
2
4Na
2

2
O
3
→2na
2
S
2
O
6
4NaI (2)Available in (1) and (2) modes: 4 Mo (er) Na
2
S
2
O
3
equivalent to 2 Mo (er) I
2
, while 2 Mo (er) I
2
equivalent to 1 Mo (er) O
2
。 That is, 1 Mo (er) Na
2
S
2
O
3
equivalent to 1/4 Mo (er) O
2
.1 ml concentration of 0.01mol/L Na
2
S
2
O
3
equivalent to the weight of O
2
available The calculation is:when the temperature is 0 degrees C and the atmospheric pressure is 101325Pa, the mg of O
2
can be converted to ml by pressing: 1 (mol) O
2
32g s 22.4L1mlO
2
s 1.429mgO
2 0.6998mlO
2
1mgO
2instrumenttriangle

latex tube

pipe
titration tube 1% starch solutionmanganese dioxide solution: MnCl
2
.5H
2
O200g dissolved in 500ml water, then add 2ml hydrochloric acid to this solution.-sodium hydroxide mixture: 180g NaOH is said to be dissolved in 500ml water and KI 50g is added to this solution. sodium sulfate standard liquid: First prepare approximately 0.01mol/L Na
2
S
2
O
3
solution (na
2
S
2
O
3
.5H
2
O 2.4823g, Na
2
CO
3
0.02g, plus newly boiled cooled distilled water to 1000ml), 8-14 days in the dark, then calibration. 。 Operation steps Take two 250ml triangular cans, one of which is placed in several large algae (first weighing fresh weight), the other bottle as a control, and then fill the two triangular cans with water, then plug in the sun, half an hour later to measure the oxygen content of the water. method is as follows: 1. Take 2 100ml triangular cans, numbered Nos. 1 and 2, and remove the water sample to be
from
bottle using a rainbow straw. Bottle 1 picks up water from the algae bottle and bottle 2 picks up water from the control bottle. Siphon tube to put on the bottom of the bottle, initially sucked out 10 ml discarded do not, water to take a full bottle, to the extreme, need to determine the exact number of milliliters of water in the bottle (can specify the number of 1 bottle of water for A, 2 bottle of water for B). 2. Take MnCl
2
0.5 ml from a pipe and insert it under the liquid surface (not to the bottom of the bottle so that too much water in the bottle does not spill and affect the results), and inject it into the water. 3. The potassium iodide-sodium hydroxide mixture was then taken from a pipet, inserted under the liquid surface according to the method, and the mixture was injected into the water. 4. Closed, oscillating. 2 hours in the dark (to produce precipitation). 5. Gently inject 3 ml of hydrochloric acid into the middle of the solution with a pipe, closed and oscillating. At this point the precipitation dissolves, the iodine frees out, and the liquid is yellow to brown. 6. Move the liquid into a 250ml triangulated flanken (to be poured out of the original bottle and rinse with distilled water) and titrate with 0.01mol/L sodium sulfate to note the required ml. because iodine and starch form a complex, resulting in its reaction to Na
2
S
2
O
3
slow, easy to add Na
2
S
2
O
3
excessive. Therefore, the titration is first titration with Na
2
S
2
O
3
until the solution is pale yellow, then add 1% starch 1-2 drops, and then continue to titrate to the blue disappear (end point). the results of the experiment, the number of milligrams of oxygen per gram of fresh weight per hour was calculated. first calculated the calibration of na
2
S
2
O
3
(concentration M, mol/L) 1 ml equivalent to O
2
mg weight is: and then calculated with siphon to 100 ml of triangulated bottle oxygen content;
calculated the oxygen content per ml of water in the blank bottle: finally calculated the amount of O
2
per hour per g of fresh weight, the number of mg per hour (table sightseeing intensity): reduced to; type: A for bottle 1 water sample volume, ml. 。 The Aml water sample taken by V for bottle 1 consumes na
2
S
2

3
ml. 。 B the volume of the water sample taken for bottle 2, ml. 。 V'Bml water sample taken for bottle 2 consumes na
2
S
2
O
3
, ml. 。 M is the calibration of the
2
S
2
O
3
concentration, mol/L. 。 V" is the volume of water in the algae bottle, ml. g is fresh algae. h for photosynthing time. 0.08 is 1 ml 0.01mol/L concentration na
2
S
2
O
3
equivalent to O
2
weight mg/ml. 0.01 is the
Na
S
2

3
, mol/L. 。