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IRINA_888 [86]
3 years ago
10

PLEASE HELP!! It’s the last day to get the assignment in!!

Chemistry
1 answer:
Blizzard [7]3 years ago
3 0

Answer:

Explanation:

Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color chage, formation of a precipitate, formation of a gas, odor change, temperature change. Or Light is given off, a permanent color change occurs, gas is given off, heat is given off, and a precipitate is formed

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KOH + HBr - KBr + H2O<br> Which is the acid in this reaction?
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HBr is a strong acid

Explanation:

KBr is a salt which makes a base . also KOH is a base

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The activation energy for the reaction NO2(g)+CO(g)⟶NO(g)+CO2(g) is Ea = 75 kJ/mol and the change in enthalpy for the reaction i
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Answer:

= 100kJ

Explanation:

The reverse reaction's activation energy of a reaction is the activation energy of the forward reaction plus ΔH of the reaction:

Ea of forward reaction =75kJ

∆H = -175 kJ/mol

Ea of reverse reaction = 75 +(-175)

= 100kJ

Note that a reverse reaction is one which can proceed in both direction depending on the conditions.

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Suggest two observations that would be made when rubidium is added to cold water.
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Answer:

1. Rubidium metal reacts very rapidly with water to form a colorless basic solution of rubidium hydroxide (RbOH) and hydrogen gas (H2).

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2 years ago
A 2.684-g sample of zinc oxide was reduced by hydrogen gas, resulting in 2. 156 g of pure zinc metal. Determine the empirical fo
Afina-wow [57]

The empirical formula of the initial zinc oxide is ZnO.

<h3>What is Empirical Formula?</h3>

The empirical formula of a compound represents the ratios of elements in a compound but not the actual numbers or arrangement of the atoms.

It is the lowest whole number ratio of the element in the compound.

<h3>How to find out the empirical formula?</h3>
  • Find out the given masses and molar masses of the elements

The molar mass of Zn = 65 gmol⁻¹

Given the mass of Zn = 2.156 g

The molar mass of Oxygen = 16 gmol⁻¹

The mass of Oxygen = Mass of a sample of zinc oxide - the mass of zinc metal

                                   = (2.684 - 2.156) g

                                   = 0.528 g

  • Find the number of moles of the elements in the compound

The number of moles is given by

n = \frac{m}{M}

where m = given mass and

M = Molar mass

Number of moles of Zinc = \frac{2.156}{65} = 0.033 moles

Number of moles of Oxygen =\frac{0.528}{16} = 0.033 moles

  • Find the simplest ratios of the elements in the compound. To find the ratios simply divide the number of moles by the lowest number of moles obtained.

Here, the number of moles is the same for both elements. Hence, the simplest ratio for Zn:O is 1:1.

Therefore, the empirical formula of zinc oxide is ZnO.

Learn more about the empirical formula:

brainly.com/question/1603500

#SPJ4

 

5 0
1 year ago
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