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BlackZzzverrR [31]
3 years ago
10

How many electrons elements are present in period 2 ?​

Chemistry
2 answers:
katrin2010 [14]3 years ago
7 0
There are 8 elements
AVprozaik [17]3 years ago
3 0
There are Eight elements
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in order to find the molar mass of an unknown compound, a research scientist prepared a solution of 0.930 g of an unknown in 125
PtichkaEL [24]

Answer:

Molar mass→ 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

Explanation:

Let's apply the formula for freezing point depression:

ΔT = Kf . m

ΔT = 74.2°C - 73.4°C → 0.8°C

Difference between the freezing T° of pure solvent and freezing T° of solution

Kf = Cryoscopic constant → 5.5°C/m

So, if we replace in the formula

ΔT = Kf . m → ΔT / Kf = m

0.8°C / 5.5 m/°C = m → 0.0516 mol/kg

These are the moles in 1 kg of solvent so let's find out the moles in our mass of solvent which is 0.125 kg

0.0516 mol/kg . 0.125 kg = 6.45×10⁻³ moles. Now we can determine the molar mass:

Molar mass (mol/kg) → 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

3 0
3 years ago
To begin, check that Reaction 1 and Forward are selected. In this reaction, hydrogen (H2) and oxygen (O2) react to form water (H
Kruka [31]

Answer:

The reaction occurs and all H2 and O2 unite to form H20

3 0
3 years ago
If 335 g water at 35.5C loses 5750 J of heat, what is the final temperature of the water?
White raven [17]

Answer:

The final temperature is  39.58 degree Celsius

Explanation:

As we know

Q = m * c * change in temperature

Specific heat of water (c) = 4.2 joules per gram per Celsius degree

Substituting the given values we get  -

5750 = 335 * 4.2 * (X - 35.5)

X = 39.58 degree Celsius

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3 years ago
Why did Dalton think it was important to use his system of symbols for the chemical elements?
Dimas [21]

Explanation:

to remind people that atoms were

4 0
4 years ago
How many moles of oxygen are in 8.25g of O?
posledela
8.25 grams of O2 has 0.258 moles of Oxygen. Here's how you figure that out:
Oxygen is one of the 7 diatomic elements, so it is normally O2.
<span>You find it's molar mass (or mass for </span>one mole<span> of it) by adding up two of the masses from the Periodic Table.</span>
6 0
4 years ago
Read 2 more answers
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