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ANEK [815]
4 years ago
10

2. Incoming wastewater, with BOD5 equal to 200 mg/L, is treated in a well-run secondary treatment plant that removes 90 percent

of the BOD. You are to run a five-day BOD test with a standard 300-mL bottle, using a mixture of treated sewage and dilution water (no seed). Assume the initial DO is 9.2 mg/L. a. Roughly what maximum volume of treated wastewater should you put in the bottle if you want to have at least 2.0 mg/L of DO at the end of the test (filling the rest of the bottle with water). (answer in mL)

Chemistry
1 answer:
Lesechka [4]4 years ago
5 0

Answer:

10.8 ml

Explanation:

The BOD is an empirical test to determine the molecular oxygen used during a specified incubation period (usually five days), for the biochemical degradation of organic matter (carbonaceous demand) and the oxygen used to oxidise inorganic matter.

See attached file

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The relatively high boiling point of water is due to water having
Verizon [17]
The answer should be hydrogen bonding. Water only has oxygen and hydrogen in it, which are both nonmetals, so you know the answer cannot be metallic or ionic. It also cannot be nonpolar because the electronegativity of the oxygens will make the molecule polar. You can also know it is hydrogen bonding because it can only take place when a hydrogen is attached to an oxygen, fluorine, or nitrogen. These bonds are very strong attractions, so the molecules are extremely hard to pull apart, creating a high boiling point. Hope that helps!
3 0
3 years ago
What is the percent of hydrogen by mass in CH4O?<br> (H:1.00 amu, C: 12.01 amu, O: 16.00 amu)
cricket20 [7]

The mass percent of hydrogen in CH₄O is 12.5%.

<h3>What is the mass percent?</h3>

Mass percent is the mass of the element divided by the mass of the compound or solute.

  • Step 1: Calculate the mass of the compound.

mCH₄O = 1 mC + 4 mH + 1 mO = 1 (12.01 amu) + 4 (1.00 amu) + 1 (16.00 amu) = 32.01 amu

  • Step 2: Calculate the mass of hydrogen in the compound.

mH in mCH₄O = 4 mH = 4 (1.00 amu) = 4.00 amu

  • Step 3: Calculate the mass percent of hydrogen in the compound.

%H = (mH in mCH₄O / mCH₄O) × 100%

%H = 4.00 amu / 32.01 amu × 100% = 12.5%

The mass percent of hydrogen in CH₄O is 12.5%.

Learn more about mass percent here:brainly.com/question/4336659

3 0
2 years ago
A certain gas at 2oC and 1.00 atm pressure fills a 4.0 container. What volume will the gas occupy at 100oC and 780 torr pressure
artcher [175]

The final volume V₂=4.962 L

<h3>Further explanation</h3>

Given

T₁=20 + 273 = 293 K

P₁= 1 atm

V₁ = 4 L

T₂=100+273 = 373 K

P₂=780 torr=1,02632 atm

Required

The final volume

Solution

Combined gas law :

P₁V₁/T₁=P₂V₂/T₂

Input the value :

V₂=(P₁V₁T₂)/(P₂T₁)

V₂=(1 x 4 x 373)/(1.02632 x 293)

V₂=4.962 L

6 0
3 years ago
How many moles would there be in 20.0 g of sodium chloride?
deff fn [24]

Answer:

20.0/1 x 1mole/58.44=0.34

                 (Atomic mass of salt)

Been a minute since I've done this, but this is how I remember doing it, soo..hope this helps!

6 0
3 years ago
Consider these changes.
Ede4ka [16]

Answer:

(a) The system does work on the surroundings.

(b) The surroundings do work on the system.

(c) The system does work on the surroundings.

(d) No work is done.

Explanation:

The work (W) done in a chemical reaction can be calculated using the following expression:

W = -R.T.Δn(g)

where,

R is the ideal gas constant

T is the absolute temperature

Δn(g) is the difference between the gaseous moles of products and the gaseous moles of reactants

R and T are always positive.

  • If Δn(g) > 0, W < 0, which means that the system does work on the surroundings.
  • If Δn(g) < 0, W > 0, which means that the surroundings do work on the system.
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<em>(a) Hg(l) ⇒ Hg(g)</em>

Δn(g) = 1 - 0 = 1. W < 0. The system does work on the surroundings.

<em>(b) 3 O₂(g) ⇒ 2 O₃(g) </em>

Δn(g) = 2 - 3 = -1. W > 0. The surroundings do work on the system.

<em>(c) CuSO₄.5H₂O(s) ⇒ CuSO₄(s) + 5H₅O(g) </em>

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<em>(d) H₂(g) + F₂(g) ⇒ 2 HF(g)</em>

Δn(g) = 2 - 2 = 0. W = 0. No work is done.

3 0
3 years ago
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