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Lelu [443]
2 years ago
8

A. When calcium metal reacts with water, the gas evolved will not catch fire, but the same gas evolved on Potassium metal to wat

er catches fire. Why?
b. An element forms an oxide X2O3 which is acidic in nature. Identify A as a metal or non-metal and write its molecular formula
Chemistry
1 answer:
Phoenix [80]2 years ago
3 0

Answer:

a. Due to the evolved hydrogen from potassium to water reaction being able to reach the flash point of the reaction temperature

b. Non-metal

The molecular formula is N₂O₃

Explanation:

a. The heat of the reaction between calcium and water is given as follows

Ca + 2 H₂O → H₂ +  Ca(OH)₂    ΔH = -431.15 kJ which is exothermic, Entropy = -125.29 J/K

The heat of the reaction between potassium and water is given as follows

2 k + 2 H₂O → 2 KOH  + H₂ ΔH = -393.15 kJ Entropy = 44.91 J/K

Therefore, the reaction between potassium and water occurs more vigorously than the reaction between calcium and water such that the flash point for the released hydrogen gas is reached in the case of potassium

b. The acidic oxides are oxides of metals or non-metals that react with water to produce an acid

Given the valence of the oxide which is +3, the oxide can be aluminium, Al or nitrogen, N, however, Al₂O₃ behaves both as an acid and a base, therefore, the likely candidate is nitrogen, which shows that X is a non-metal

The molecular formula is therefore;

N₂O₃

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Define an arrhenius base and describe properties of bases. use an example to explain how an arrhenius base will behave in water.
murzikaleks [220]

An Arrhenius base is a molecule that when dissolved in water will break down to yield an OH^- or hydroxide in solution.

<h3>What is Arrhenius base?</h3>

An Arrhenius base is a compound that increases the OH− ion concentration in aqueous solution.

An Arrhenius base is a substance that, when dissolved in an aqueous solution, increases the concentration of hydroxide, or OH^-, ions in the solution.

Bases Properties

Arrhenius bases that are soluble in water can conduct electricity.

Bases often have a bitter taste and are found in foods less frequently than acids. Many bases, like soaps, are slippery to the touch.

Bases also change the colour of indicators. Red litmus turns blue in the presence of a base (see figure below), while phenolphthalein turns pink.

Some bases react with metals to produce hydrogen gas.

Acids (pH < 7.0) react with bases (pH > 7.0) to produce a salt and water. When equal moles of an acid and a base are combined, the acid is neutralized by the base. The resulting mixture will have a more neutral pH.

An Arrhenius acid is a substance that dissociates in water to form hydrogen ions or protons. In other words, it increases the number of H+ ions in the water. In contrast, an Arrhenius base dissociates in water to form hydroxide ions, OH^-.

Example, sodium hydroxide, is added to an aqueous solution. NaOH dissociates into sodium, Na^+, and hydroxide, OH^-, ions.

Learn more about the Arrhenius bases here:

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4 0
2 years ago
If 20.0 mL of a 0.0800 M HNO3, 35.0 mL of a 0.0800 M KSCN, and 40.0 mL of a 0.0800 M Fe(NO3)3 are combined, what is the initial
Tems11 [23]

Answer:

0.0295M

Explanation:

As you can see, in the mixture you have KSCN and other compounds. The KSCN in solution is dissolved in K⁺ ions and SCN⁻ ions. That means initial concentration of SCN⁻ ions is the same of KSCN, 0.0800M.

You are adding 35.0mL of this solution and the total volume of the mixture is 20.0mL + 35.0mL + 40.0mL = 95.0mL.

That means you are diluting your solution 95.0mL / 35.0mL = 2.714 times.

And the concentration of SCN⁻ is:

0.0800M / 2.714 =

<h3>0.0295M </h3>

4 0
3 years ago
Which of the following pieces of laboratory glassware should be used to most accurately measure out a 25.00 ml sample of a solut
wel

Answer:

The correct answer is 25 mL graduated cylinder (it should be used in all the cases)

Explanation:

In order to measure 25.00 ml sample of a solution it should be used a 25 mL graduated cylinder, as it is previously and properly calibrated. The other laboratory glassware, beaker and erlenmeyer, have graduations which are approximate, so they are used when exact volumes are not needed.

ii) graduated cylinder has the least uncertainly. It is more accurate than a beaker or erlenmeyer (to within 1%)

iii) A 25 mL graduated cylinder should be used because it is the most accurate lab glassware (between those were mentioned: beaker, erlenmeyer).

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