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Ivanshal [37]
2 years ago
14

A student wants to carry out flame tests on these three chemicals. Describe how to carry out a flame test.

Chemistry
1 answer:
neonofarm [45]2 years ago
3 0

Answer:

Flame test is one of the chemical tests that can be used to identify a metal or metaloid

in an ionic compound.

Explanation:

Flame test is guided by a principle that when an unknown metal is heated, heat of the flame converts the metal ions into atoms which become excited and emit visible light.

To carry out flame test in a laboratory the following instruments are required:

--> a wire loop

--> Bunsen burner

--> the chemical compound under observation

--> protective wears.

The procedure involves the following steps:

--> turn on the Bunsen burner and adjust the barrel of the burner roll the flame is blue.

--> using a clean wire loop deep into a beaker containing hydrochloric acid.

--> to ensure that the loop is clean, it will give the same blue colour of the flame when heated.

--> deep the loop in the acid again and then use it to pick few grains of the metal.

--> place the wire loop in the side of the flame and observe the colour of the flame.

Result of flame tests of some metallic ion will show the following:

--> sodium ion will give yellow colour flame

--> potassium ion will give lilac colour flame

--> calcium ion will give orange-red colour flame

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A voltaic cell utilizes the following reaction: 4Fe2+(aq)+O2(g)+4H+(aq)→4Fe3+(aq)+2H2O(l). What is the emf of this cell under st
Leviafan [203]

Answer:

0.46 V

Explanation:

The emf for the cell is given by:

Eº cell = Eº oxidation + Eº reduction

From the  given balanced chemical equation, we can deduce that Fe²⁺ has been oxidized to Fe³⁺, and O reduced  from 0 to negative 2, according to the half cell reactions:

4Fe²⁺  ⇒ Fe³⁺ + 4e⁻           oxidation

O₂ + 4H⁺ + 4 e⁻ ⇒ 2 H₂O   reduction

From reference tables for the standard reduction potential, we get

Eº red Fe³⁺ / Fe²⁺   Eºred = 0.77 V  

Eº red O₂ / H₂O      Eºred = 1.23 V

Now all we need to do is change the sign of Eº reduction for the species being oxidized ( Fe²⁺ ) and add it to Eº reduction  O₂:

Eº cell =   Eº oxidation + Eº reduction = - (0.77 V ) + 1.23 V = 0.46 V

5 0
3 years ago
C time
lesya692 [45]

Answer:

B. Spring balance - a device used for measuring the weight or force of gravity acting on an object.

Explanation:

A Force is any interaction that changes the motion or position of an obkpjectbthatbit is interacting with. Whenever there is an interaction between two objects, there is a force exerted by each of the objects on one themselves.

Forces are generally divided into contact forces and non-contact over field forces.

In contact forces, the two objects physically in contact with each other. Examples of contact forces are push or pull forces, frictional forces, tensional forces, spring forces, etc.

Non-contact forces are forces in which the two objects interacting do no need to be physically in contact with one another. Examples include, gravitational forces, magnetic forces, electrical forces, etc.

Instruments used in measuring forces are known as force gauges.

From the instruments listed above:

A. A ruler is an instrument used in measuring length

B. Spring balance is a device used for measuring the weight or force of gravity acting on an object.

C. A thermometer is an instrument used in measuring temperature

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4 0
3 years ago
a compound has a molar mass of 129 g/mol if its empirical formula is C2H5N then what is the molecular formula
Elena-2011 [213]

Given :

A compound has a molar mass of 129 g/mol .

Empirical formula of compound is C₂H₅N .

To Find :

The molecular formula of the compound.

Solution :

Empirical mass of compound :

M_e = ( 2 \times 12 ) + ( 5 \times 1 ) + (  1  \times 14 )\\\\M_e = 43\ gram/mol

Now, n-factor is :

n = \dfrac{M}{M_e}\\\\n = \dfrac{129}{43}\\\\n = 3

Multiplying each atom in the formula by 3 , we get :

Molecular Formula, C₆H₁₅N₃

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ArbitrLikvidat [17]

Answer:

I think it's C. Grass. :)

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Answer:

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