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NNADVOKAT [17]
3 years ago
7

When silver coins are found in ancient shipwrecks, they are coated with a black crust. What question could you ask to help you d

ecide whether the silver underwent a chemical change or a physical change?
Chemistry
1 answer:
Aleks04 [339]3 years ago
5 0
You could ask whether the black crust is a new substance formed from silver underwent a chemical change because a chemical change produces a new substance.
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Which is an element? ... air ...carbon dioxide ...hydrogen ...water Description
Natalka [10]
All Elements are obtained in the periodic table & water is Not an element it is a compound.
5 0
3 years ago
Read 2 more answers
A 7.0 g sample of a hydrocarbon (a molecule that has only hydrogen and carbon) is subject to combustion analysis. The mass of CO
Akimi4 [234]

Answer: The empirical formula for the given compound is CH_2

Explanation:

The chemical equation for the combustion of compound having carbon and hydrogen follows:

C_xH_y+O_2\rightarrow CO_2+H_2O

where, 'x' and 'y' are the subscripts of carbon and hydrogen respectively.

We are given:

Mass of CO_2=22.0g

We know that:

Molar mass of carbon dioxide = 44 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 22.0 g of carbon dioxide, \frac{12}{44}\times 22.0=6g of carbon will be contained.

For calculating the mass of hydrogen:

Mass of hydrogen = Mass of sample - Mass of carbon

Mass of hydrogen = 7.0 g - 6 g

Mass of hydrogen = 1.0 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon =\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{6g}{12g/mole}=0.5moles

Moles of Hydrogen = \frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1.0g}{1g/mole}=1.0moles

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.5 moles.

For Carbon = \frac{0.5}{0.5}=1

For Hydrogen  = \frac{1.0}{0.5}=2

Step 3: Taking the mole ratio as their subscripts.

The ratio of Fe : C : H = 1 : 2

Hence, the empirical formula for the given compound is C_{1}H_{2}=CH_2

4 0
3 years ago
Burning one gallon of gasoline releases 20 pounds of CO2 into the air. Harry’s compact car can travel 25 miles on one gallon of
son4ous [18]
There are several information's already given in the question. Based on those information's, the answer can be easily deduced.
Amount of gasoline required by Harry's car to travel 25 miles = 1 gallon
Then
amount of gasoline required
by Harry's car to travel 15000 miles = 15000/25
                                                         = 600 gallons
So 
Amount of CO2 released by burning 1 gallon of gasoline = 20 pounds
Then
Amount of CO2 released
by burning 600 gallon of gasoline = 600 * 20
                                                      = 12000 pounds
From the above deduction, it can be concluded that the amount of CO2 that will be added by Harry's car to the atmosphere is 12000 pounds.
5 0
3 years ago
What is the percent yield of NaCl if 31g of CuCl2 reacts with excess NaNo3 to produce 21.2g of NaCl
Valentin [98]
The answer is 78.7% yield.
3 0
3 years ago
A bottle is partly filled with liquid water, sealed shut, and then placed under a heat lamp. The volume of the liquid water even
ANTONII [103]

Because the rate at which water vapour condenses gets increase slowly to get equal to the rate of evaporation of the water.

Explanation:

When a bottle is partly filled with liquid water is leaves space for vapours to escape and get condensed equally.

When sealed and kept below the lamp the rate of condensation increases due to the empty space in the bottle for getting vapours cool down.

A point arrives when evaporation equates the condensation of the liquid in bottle becomes stable because vapours cannot pass the bottle eventually condense and become liquid.

6 0
3 years ago
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