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Zanzabum
3 years ago
5

Explain in terms of chemical reactivity why the elements in group 18 on the modern periodic table were not identified by Mendele

ev's at that time
Chemistry
1 answer:
Makovka662 [10]3 years ago
6 0

Answer:

elements tend not to react with other elements, there were no oxide compounds for Mendeleev to study. –Group 18 elements are generally unreactive. sodium ion is smaller because the sodium atom lost one electron. –An Na+ ion is smaller because it has one fewer electron shell.

Explanation:

can you me as brainliest if its right? i just need a few more to rank up! ^-^

Also have a great day and good luck in your studies!

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Calculate the osmotic pressure associated with 50.0 g of an enzyme of molecular weight 98 g/mol dissolved in water to give 2600
andrew-mc [135]

Answer:

π = 4,882 atm

Explanation:

To calculate the osmotic pressure (π), the <em>Van´t Hoff equation</em> must be used, which is:

π x V = n x R x T

<em>Where: </em>

• π: Osmotic pressure, which is the difference between the levels of the solution and the pure solvent through a semipermeable membrane, which allows the passage of the solvent but not the solute

• V: Volume of the solution, in liters unit

• n: Number of moles of solute

• R: Constant of ideal gases, equal to 0.08206 L.atm / mol.K

• T: Absolute temperature, in Kelvin degrees

With the data you provide you can calculate the osmotic pressure by clearing it from the equation, we would be equal to:

π = (n x R x T) / V

However, all data must first be converted to the corresponding units in order to replace the values ​​in the equation.

<em>Solution volume ⇒ go from mL to L: </em>

1000 mL of solution ____ 1 L

2600 mL of solution _____ X = 2.6 L

Calculation: 2600 mL x 1 L / 1000 mL = 2.6 L

<em>Temperature ⇒ Go from ° C to K </em>

T (K) = t (° C) + 273.15 = 30.0 ° C + 273.15 = 303.15 K

<em>Number of moles of solute ⇒</em> <em>It can be calculated since we have the mass of the enzyme and its molecular mass: </em>

98.0 g of enzyme ____ 1 mol

50.0 g of enzyme _____ X = 0.510 moles

Calculation: 50.0 g x 1 mol / 98.0 g = 0.510 moles

Now, you can replace the values ​​in the Van´t Hoff equation and you will get the result:

 π = (n x R x T) / V

π = (0.510 mol x 0.08206 L.atm / mol.K x 303.15 K) / 2.6 L = 4.882 atm

Therefore, <em>the osmotic pressure will be 4,882 atm</em>

3 0
3 years ago
Which types of bond is formed between the two chlorine atoms in a chlorine molecule?
madam [21]
They achieve stable structures by sharing their single, unpaired electron.
7 0
3 years ago
Which of the following is true if the net force on an object is zero? (1 pt) a. The object must be at rest. b. The object’s spee
prohojiy [21]

Explanation:

the object must be at rest

5 0
3 years ago
Calculate the ph of a solution with a [H3O+]=5.6x10-9M
Kisachek [45]

Answer:

               pH  =  8.25

Explanation:

                   The acidity or basicity of a solution is measured by its pH. The pH scale ranges from 0 to 14. Solutions having pH from 0-6.9 are considered acidic, at 7 neutral and basic when ranging from 7.1-14.

pH is calculated as,

                                 pH  =  - log [H⁺]   ---- (1)

Where;

            [H⁺]  =  concentration of Acid

Also, for bases pH i calculated using following formula,

                                 pH  =  14 - pOH

Therefore, Putting value of H⁺ in equation 1,

                                 pH  =  - log [5.6 × 10⁻⁹]

                                pH =  8.25

The solution provided is basic in nature.

6 0
3 years ago
How much heat is needed to raise the temperature of 55.0 g sample of water by 65.0 oC.
sveticcg [70]

Answer: 14943.5 J

Explanation:

The quantity of heat energy (Q) required to raise the temperature of a substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)

Thus, Q = MCΦ

Given that,

Q = ?

Mass of water = 55.0g

C = 4.18 J/g°C

Φ = 65.0°C

Then, Q = MCΦ

Q = 55.0g x 4.18 J/g°C x 65.0°C

Q = 14943.5 J

Thus, 14943.5 joules of heat is needed to raise the temperature of water.

3 0
3 years ago
Read 2 more answers
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