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3 years ago

Enter a balanced chemical equation for the reaction between potassium metal and liquid water.

Chemistry

1 answer:

Oksanka [162]3 years ago

6 0

Answer:

2K (s) + 2H₂O (l) → 2KOH (aq) + H₂(g)↑

Explanation:

<u>1) Word equation (given)</u>

Potassium + water → ?

<u>2) Kind of reaction</u>

<em>Potassium</em> is an alkali metal.

This is a single replacement reaction.

Alkali metals is the group of metals in the group 1 of the periodic table. These are the most active metals, meaning that they react violently with water releasing hydrogen gas.

Alkali metals can lose an electron to form compounds with oxidation number +1.

The general equation for the reaction of an alkali metal and water is:

Metal + Water → hydroxide + gaseous hydrogen

X + H₂O → XOH(aq) + H₂ (g) ↑

<u>3) Chemical equation</u>

K (s) + H₂O (l) → KOH(aq) + H₂(g)↑

<u>4) Balance</u>

2K (s) + 2H₂O (l) → 2KOH(aq) + H₂(g)↑

There is the same number of each atom on both sides: 2 K in the left and in the right, 4 H in the left and in the right, and 2 oxygen in the left and in the right. So, the equation is balanced.

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Calculate the freezing point of a solution containing 5.0 grams of KCl and 550.0 grams of water. The molal-freezing-point-depres

yulyashka [42]

<u>Answer:</u> The freezing point of solution is -0.454°C

<u>Explanation:</u>

Depression in freezing point is defined as the difference in the freezing point of pure solution and freezing point of solution.

The equation used to calculate depression in freezing point follows:

$\Delta T_f=\text{Freezing point of pure solution}-\text{Freezing point of solution}$

To calculate the depression in freezing point, we use the equation:

$\Delta T_f=iK_fm$

Or,

$\text{Freezing point of pure solution}-\text{Freezing point of solution}=i\times K_f\times \frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ (in grams)}}$

where,

Freezing point of pure solution = 0°C

i = Vant hoff factor = 2

$K_f$ = molal freezing point elevation constant = 1.86°C/m

$m_{solute}$ = Given mass of solute (KCl) = 5.0 g

$M_{solute}$ = Molar mass of solute (KCl) = 74.55 g/mol

$W_{solvent}$ = Mass of solvent (water) = 550.0 g

Putting values in above equation, we get:

$0-\text{Freezing point of solution}=2\times 1.86^oC/m\times \frac{5\times 1000}{74.55g/mol\times 550}\\\\\text{Freezing point of solution}=-0.454^oC$

Hence, the freezing point of solution is -0.454°C

3 0

3 years ago

As the vibration of molecules increases, the _____ of the substance increases.

garik1379 [7]

The temperature,internal energy,and kinetic energy will all increase

5 0

3 years ago

A 1500 kg race car accelerates at a rate of about 9M /s2 as to how much force does the engine need to create for this to happen

IgorC [24]

Answer:

13500 N

Explanation:

According to newtons second law of motion

mass m =1500 Kg

a = 9m/s^2

Force F = mass m × acceleration a

F = 1500×9= 13500 N

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2 years ago

HELPPPPPPPP <br> how many atoms in sodium hydrate

musickatia [10]

There are 4 atoms in sodium hydrate

5 0

3 years ago

a serving of a particular fruit dessert contains 20.0 g of sugar. if all the sugar is sucrose, c12h22o11, how many molecules of

Harrizon [31]

Taking into account the definition of Avogadro's number and molar mass, 3.49334×10²² molecules of sucrose are present.

<h3>Definition of molar mass</h3>

The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.

<h3>Avogadro's Number</h3>

Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole. Avogadro's number applies to any substance.

<h3>Molecules of sugar in this case</h3>

In first place, the molar mass of sucrose is 342 g/mole. So, you can apply the following rule of three: If by definition of molar mass 342 grams of the compound are contained in 1 mole, 20 grams of the compound are contained in how many moles?

$amount of moles=\frac{20 gramsx1 mole}{342 grams}$

<u><em>amount of moles= 0.058 moles</em></u>

Now, considering the Avogadro's number, you can apply the following rule of three: If 1 mole of the compound contains 6.023×10²³ molecules, 0.058 moles contains how many molecules?

amount of moleculas= (6.023×10²³ molecules × 0.058 moles)÷ 1 mole

<u><em>amount of molecules= 3.49334×10²² molecules</em></u>

Finally, 3.49334×10²² molecules of sucrose are present.

Learn more about

molar mass:

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Avogadro's Number:

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