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kozerog [31]
3 years ago
8

Which of the following is a pure substance?AirBloodCopperWood​

Chemistry
2 answers:
krek1111 [17]3 years ago
4 0

Answer:

copper

Explanation:

its an element, its not mixed with anything else

Schach [20]3 years ago
4 0

The answer is "Copper" or option C. Air, and blood aren't pure substances but mixtures, wood is also a mixture which means the answer is copper. Pure Substances are is matter with composition and distinct chemical properties.

Hope this helps.

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The average propane cylinder for a residential grill holds approximately 18 kg of propane. how much energy (in kj) is released b
Angelina_Jolie [31]
Let's begin with the basic values  that will be used in the solution.

The formula of propane is C3H8. It is an alkane, a hydrocarbon with the general formula of CnH2n+2. Notice that hydrocarbons have only Carbon and Hydrogen atoms. Its molar mass (M) is 44 g.

Molar Mass Calculation is done as like that
C=12 g/mol, H=1 g/mol. 1 mole propane has 3 moles Carbon atoms and 8 mole Hydrogen atoms. M(
C3H8)= 3*12+ 8*1= 44 g

Combustion reaction of hydrocarbons gives carbon dioxide and water by releasing energy. That energy is called as enthalpy of combustion (
ΔHc°).  

ΔHc° of propane equals -2202.0 kj/mol. Burning of 1 mole C3H8 releases 2202 kj energy. Minus sign only indicates that the energy is given out ( an exothermic reaction ).

Let's write the combustion reaction.
C3H8 + O2 ---> CO2 + H20 (unbalanced) 
ΔHc° = -2202 kj/mol

Now, we calculate mole of 20 kg propane. Convert kilogram into gram since we use molar mass is defined in grams.
mole=mass/molar mass ; n=m/M ; n= 20000 g /44 (g/mol)=454 mole

1 mole propane releases 2202 kj energy.
454 mole propane release 2202 kj *454= 1000909 kj

The answer is 1000909 kj.



6 0
3 years ago
The downward force acting on an object in free fall is the force of
Eduardwww [97]
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6 0
3 years ago
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The reaction of removing CO2 using LiOH is the following:

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worty [1.4K]

In france grapes are 1.83 euros per kilogram. What is the cost of grapes in dollars per pound if the exchange rate is 1.40 dollars per euro

1.83 euros x 1.40 = 2.56 dollars

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6 0
3 years ago
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nlexa [21]

Answer:

Hi

Explanation:

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