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ValentinkaMS [17]
3 years ago
10

What is the difference between physical and chemical change?

Chemistry
2 answers:
zmey [24]3 years ago
8 0
A physical Change is when you change the form, but not the object. such as when you grind wood, you get wood chips. same thing different form. a chemical Change is When You change the substance by adding another substance
Vikki [24]3 years ago
6 0
There are several differences between<span> a </span>physical and chemical change<span> in matter or substances. A </span>physical change<span> in a substance doesn't </span>change<span> what the substance is. In a </span>chemical change<span> where there is a </span>chemical<span> reaction, a new substance is formed and energy is either given off or absorbed.</span>
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3 years ago
You are managing a city that needs to upgrade its disinfection basin at your 40 MGD surface water drinking water treatment plant
nignag [31]

Solution :

According to Chick's law

$\frac{N_t}{N_0}=e^{-k'C^n t}$

where, t = contact time

            c = concentration of disinfectant

            k' = lethality coefficient = 4.71

            n = dilution coefficient = 1

            4 log removal = % removal = 99.99

$\frac{N_t}{N_0}=\frac{\text{bacteria remaining}}{\text{bacteria initailly present}}$

      = 1 - R

      = 1 - 0.9999

Now for plug flow reactor contact time,

$\tau =\frac{V}{Q} =\frac{75000}{40 \times 10^6}$

          = 0.01875 days

          = 27 minutes

For CSTR, $\tau =\frac{V}{Q} =\frac{150000}{40 \times 10^6}$

                             $=3.75 \times 10^{-3}$ days

                            = 5.4 minute

There are 3 reactors, hence total contact time = 3 x 5.4

                                                                            = 16.2 minute

Or $\frac{N_t}{N_0}=e^{-k'C^n t}$

or $(1-0.9999)=e^{-4.71 \times C \times t}$

∴ C x t = 1.955

For PFR, $t_1 = 27 $ min

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For CSIR, $t_2=16.2$ min

$C=\frac{1.955}{16.2} = 0.1206$ mg/L

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$=\frac{0.072 \times 40 \times 10^6 \times 3.785}{10^6}$      (1 gallon = 3.785 L)

= 18.25 kg/day

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3 0
3 years ago
What is the mass of a 1.68-l sample of a liquid that has a density of 0.921g/ml?
Gwar [14]
Hey there!

Volume in mL :

1.68 L  * 1000 => 1680 mL

Density = 0.921 g/mL

Therefore:

Mass = density * Volume

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7 0
3 years ago
How many hydrogen grams can be obtained if
kipiarov [429]

hi im breanna

Answer:

The mole is simply a very large number that is used by chemists as a unit of measurement.

Explanation:

The mole is simply a very large number,  

6.022

×

10

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, that has a special property. If I have  

6.022

×

10

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hydrogen atoms, I have a mass of 1 gram of hydrogen atoms . If I have  

6.022

×

10

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H

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molecules, I have a mass of 2 gram of hydrogen molecules. If I have  

6.022

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C

atoms, I have (approximately!) 12 grams.

The mole is thus the link between the micro world of atoms and molecules, and the macro world of grams and litres, the which we can easily measure by mass or volume. The masses for a mole of each element are given on the periodic table as the atomic weight. So, if have 12 g of  

C

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O

2

are required to react with the  

C

, which I could measure by mass or by volume.

5 0
3 years ago
Look at the questions below and decide which is declarative.
Yuliya22 [10]
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