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3 years ago

Which option correctly orders the elements by increasing reactivity? Hint: Review your periodic table.

Chemistry

1 answer:

myrzilka [38]3 years ago

5 0

Answer is: Li < Na < K.

Lithium (Li), sodium (Na) and potassium (K) are alkaline metals.

Alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons (one electron).

Potassium has lowest ionization energy and it is most reactive, because valcense electrons is farthest from nucleus.

Electron configuration of lithium atom: ₃Li 1s² 2s¹.

Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.

Electron configuration of potassium is: ₁₉K 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹.

The ionization energy (Ei) is the minimum amount of energy required to remove the valence electron, when element lose electrons, oxidation number of element grows (oxidation process).

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A 2.5% (by mass) solution concentration signifies that there is of solute in every 100 g of solution. 2. therefore, when 2.5% is

Stels [109]

Answer #1. A 2.5% (by mass) solution concentration signifies that there is 2.5 grams of solute in every 100 g of solution.
To calculate 2.5% by mass solution, we divide the mass of the solute by the mass of the solution and then multiply by 100.

Answer #2. therefore, when 2.5% is expressed as a ratio of solute mass over solution mass, that mass ratio would be 2.5/100 or 2.5 grams of solute/100 grams of solution.
This means that weighing out 2.5 grams of solute and then adding 97.5 grams of solvent would make a total of 100 gram solution:
mass of solute / mass of solution = 2.5g solute / (2.5g solute + 97.5g solvent)
= 2.5g solute / 100g solution

Answer#3. a solution mass of 1 kg is 10 times greater than 100 g, thus 1kg of a 2.5% ki solution would contain 25 grams of ki.
Since 1000 grams is 1 kg, we multiply 10 to each mass so that 100 grams becomes
1000grams:
mass of solute / mass of solution = 2.5g*10 / [(2.5g*10) + (97.5g*10)]
= 25g solute/(25g solute + 975g solvent)
= 25g solute/1000g solution
= 25g solute/1kg solution

6 0

4 years ago

Calculate ΔH for the reaction: C(graphite) + 2H 2(g) + 1/2 O 2(g) => CH 3OH(l) Using the following information: C(graphite) +

Alika [10]

Answer:

$\Delta H$ for the given reaction is -238.7 kJ

Explanation:

The given reaction can be written as summation of three elementary steps such as:

$C(graphite)+O_{2}(g)\rightarrow CO_{2}(g)$ $\Delta H_{1}= -393.5 kJ$

$2H_{2}(g)+O_{2}(g)\rightarrow 2H_{2}O(l)$ $\Delta H_{2}= (2\times -285.8)kJ$

$CO_{2}(g)+2H_{2}O(l)\rightarrow CH_{3}OH(l)+\frac{3}{2}O_{2}(g)$ $\Delta H_{3}= 726.4 kJ$

---------------------------------------------------------------------------------------------------

$C(graphite)+2H_{2}(g)+\frac{1}{2}O_{2}(g)\rightarrow CH_{3}OH(l)$

$\Delta H=\Delta H_{1}+\Delta H_{2}+\Delta H_{3}=-238.7 kJ$

4 0

4 years ago

What mass of au is produced when 0.0500 mol of au2s3 is reduced completely with excess h2?

olga_2 [115]

The mass of Au is 19.7 g

The chemical reaction may be

Au₂S₃ + 3H₂ → 2Au + 3H₂S

1 mole of Au₂S₃ gives 2 mole of Au

Then 0.0500 mol of Au₂S₃ gives

0.0500 × 2 / 1

= 0.10 moles.

To find mass

Mass = moles × molar mass

Moles = 0.10.

Molar mass = 197 g

Mass = 0.10 × 197

= 19.7 g

Hence the mass of Au produces is 19.7 g

Learn more about mass on

brainly.com/question/24550995

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7 0

2 years ago

What is the mass of 0.2 moles of ethanol

Verdich [7]

Answer:

Answer is 9.2 grams

Explanation:

Molar mass of ethanol

${ \bf{CH _{3}CH_{2}OH}} = (12 \times 2) + (6 \times 1) + (16) \\ = 46 \: g$

for moles:

${ \sf{1 \: mole \: of \: ethanol \: weighs \: 46 \: g}} \\ { \sf{0.2 \: moles \: weigh \: (0.2 \times 46) \: g}} \\ = 9.2 \: g$

4 0

3 years ago

How long will a 25.00 g

charle [14.2K]

Answer:

Hope it helps.

Explanation:

It decays by beta particle emission into xenon-131. After eight days have passed, half of the atoms of any sample of iodine-131 will have decayed, and the sample will now be 50% iodine-131 and 50% xenon-131

3 0

3 years ago