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34kurt
3 years ago
13

What does control group mean

Chemistry
1 answer:
fiasKO [112]3 years ago
7 0
A control group is the group in an experiment that does not receive any sort of change, to then be compared to the other treated objects at the end of the study.
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Model describe how you would show j.j. thomson's model of the atom using small beads and clay
faltersainse [42]
Make a ball of clay and embed small beads throughout it. The plum pudding model.
5 0
3 years ago
___AsCl3+____H2S-->___As2S3+___HCI​
Alex17521 [72]

Answer:

2 AsCl₃ + 3 H₂S → As₂S₃ + 6 HCl

Explanation:

When we balance a chemical equation, what we are trying to do is to achieve the same number of atoms for each element on both sides of the arrow. On the right of the arrow is where we can find the products, while the reactants are found on the left of the arrow.

We usually balance O and H atoms last.

AsCl₃ + H₂S → As₂S₃ +HCl

<u>reactants</u>

As --- 1

Cl --- 3

H --- 2

S --- 1

<u>products</u>

As --- 2

Cl --- 1

H --- 1

S --- 3

2 AsCl₃ + H₂S → As₂S₃ +HCl

<u>reactants</u>

As --- 2

Cl --- 6

H --- 2

S --- 1

<u>products</u>

As --- 2

Cl --- 1

H --- 1

S --- 3

The number of As atoms is now balanced.

2 AsCl₃ + 3 H₂S → As₂S₃ +HCl

<u>reactants</u>

As --- 2

Cl --- 6

H --- 6

S --- 3

<u>products</u>

As --- 2

Cl --- 1

H --- 1

S --- 3

The number of S atoms is now equal on both sides.

2 AsCl₃ + 3 H₂S → As₂S₃ + 6 HCl

<u>reactants</u>

As --- 2

Cl --- 6

H --- 6

S --- 3

<u>products</u>

As --- 2

Cl --- 6

H --- 6

S --- 3

The equation is now balanced.

3 0
3 years ago
Water and phosphorus with a total mass of 200 grams are added to a flask like the one below and then the flask is sealed with a
ohaa [14]

Answer:

h20 o3vbjbxhnnhbnkknnchemesry

8 0
3 years ago
8. What volume (ml) of a 5.45 M lead nitrate solution must be diluted to 820.7 ml to make a
Ganezh [65]

212 ml of lead nitrate is required to prepare a dilute solution of 820.7 ml of lead nitrate.

Answer:

Option A.

Explanation:

Similar to Avagadro's law, there is another law termed as dilution law. As the product of volume and normality of the reactant is equal to the product of volume and normality of the product from the Avagadro's law. In dilution law, it will be as product of volume and concentration of the solute of the reactant is equal to the product of volume and concentration of solution.

C_{1} V_{1} =C_{2} V_{2}

So, as per the given question C1 = 5.45 M of lead nitrate and V1 has to be found. While C2 is 1.41 M of lead nitrate and V2 is 820.7 ml.

Then, (5.45*V_{1} ) = (820.7*1.41)

V_{1}=\frac{820.7*1.41}{5.45}=  212.33 ml

So nearly 212 ml of lead nitrate is required to prepare a dilute solution of 820.7 ml of lead nitrate.

3 0
3 years ago
Calculate the ph of the solution made by adding 0.50 mol of hobr and 0.30 mol of kobr to 1.00 l of water. the value of ka for ho
nikdorinn [45]
To fully understand the problem, we use the ICE table to identify the concentration of the species. We calculate as follows:

Ka = 2.0 x 10^-9 = [H+][OBr-] / [HOBr] 

HOBr  = 0.50 M 
KOBr  = 0.30 M = OBr-

<span>     HOBr + H2O <-> H+ + OBr- </span>
<span>I     0.50        -              0          0.30 </span>
<span>C       -x                        x             x 
</span>---------------------------------------------
<span>E(0.50-x)                    x       (0.30+x) </span>

<span>Assuming that the value of  x is small as compared to 0.30 and 0.50 </span>

<span>Ka = 2.0 x 10^-9 = x (0.30) / 0.50) </span>

<span>x = 3.33 x 10^-9 = H+</span>
pH = 8.48
3 0
4 years ago
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