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Ivanshal [37]
3 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]3 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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2) Find the volume that 2.0 moles of H2 will occupy at STP?
Rom4ik [11]

Answer:

V = 44.85 L

Explanation:

Given data:

Volume of H₂ = ?

Number of moles of H₂ = 2.0 mol

Given temperature = 273.15 K

Given pressure = 1 atm

Solution:

Formula:

PV = nRT

P = Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

By putting values,

1 atm × V = 2.0 mol × 0.0821 atm.L/ mol.K  × 273.15 K

V = 44.85 atm.L / 1 atm

V = 44.85 L

4 0
3 years ago
Which statement is true about the activity series? (5 points)
coldgirl [10]

Answer: Correct statements are given below:

1) In activity series elements are listed according to their reactivity.

2) Nuclear reaction in which low atomic nuclei fuse to form a heavier nucleus with the release of energy. Nuclear fusion reaction occurs in the sun.

3) C3H8 + 5O2 → 3CO2 + 4H2O is the example of a combustion reaction.

4) 2Fe + O2 → 2FeO is the example of synthesis reaction. In synthesis reaction is a type of reaction in which two reactants combine to form a single product.

3 0
4 years ago
Read 2 more answers
Calculate the atomic mass of gallium, symbol Ga. Gallium has two isotopes: Ga-69 and Ga-71. The relative abundance of Ga-69 is 6
amm1812

Answer:

The atomic mass of gallium (Ga) = <u>69.723 g/mol</u>

Explanation:

Given: Two isotopes of Gallium (Ga) are Gallium-69 (⁶⁹Ga) and Gallium-71 (⁷¹Ga)

<u>For ⁶⁹Ga: </u>

Relative abundance = 60.12% = 60.12 ÷ 100 = 0.6012; Atomic mass = 68.9257 g/mol

<u>For ⁷¹Ga:</u>

Relative abundance = 39.88% = 39.88 ÷ 100 = 0.3988; Atomic mass = 70.9249 g/mol

∴ The atomic mass of Ga = (Relative abundance of ⁶⁹Ga × Atomic mass of ⁶⁹Ga) + (Relative abundance of ⁷¹Ga × Atomic mass of ⁷¹Ga)

⇒ Atomic mass of Ga = (0.6012 × 68.9257 g/mol) + (0.3988 × 70.9249 g/mol) = <u>69.723 g/mol</u>

<u>Therefore, the atomic mass of gallium (Ga) = 69.723 g/mol</u>

8 0
4 years ago
An important difference between fuel cells and batteries is that batteries _______. Select the correct answer below: do not requ
aliya0001 [1]

Answer: the correct option is that batteries (do NOT require a continuous source of fuel).

Explanation:

A battery can be classified as an electrochemical cell that has the ability to produce electric current. They do NOT require a continuous supply of fuel because it contains all the reactants needed to produce electricity. Below are some examples of batteries that are commonly used:

--> Primary battery: This is a single use battery because it can't be recharged. A typical example is the dry cell.

--> Secondary battery: This type of battery can be recharged. They are used as a power source for smartphones, electronic tablets, and automobiles.

A FUEL CELL is known as a device that converts chemical energy into electrical energy. Fuel cells are similar to batteries but require a continuous source of fuel, often hydrogen. They will continue to produce electricity as long as they are constantly resupplied with reactants. Hydrogen fuel cells have been used to supply power for satellites, space capsules, automobiles, boats, and submarines.

4 0
3 years ago
Which of the following can be characterized as a physical change?
Taya2010 [7]

Answer:

D. Sweat evaporates from your skin

Explanation:

A physical change is a reversible process, no new substance is formed. A physical change does not affect the chemical composition of a substance.

Sweat evaporation from the skin is a physical change, because the change that occur is merely a change of state, Liquid to Gaseous state, no new substance is formed.

7 0
4 years ago
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