Answer:
That unknown substance is water
Explanation:
A combustion reaction is a reaction that reacts in the presence of oxygen molecules. Methane will release -3115 kJ/mol of heat.
<h3>What is a combustion reaction?</h3>
A combustion reaction includes the reaction between the chemical reactant and oxygen molecule to produce the product. The combustion reaction between methane and oxygen is given as:
CH₄(g) + 2O₂ (g) → CO₂(g) + 2H₂O (l), ΔH = -890 kJ/mol
The stoichiometry coefficient from the reaction gives 1 mole of methane releases -890 kJ/mol enthalpy.
So, 3.5 moles methane will release = 3.5 × -890 = -3115 kJ/mol
Therefore, -3115 kJ/mol of heat is released.
Learn more about combustion reaction here:
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Answer:
independant=variable that has changed
dependant=variable affected by the change
water=independant, because if you put too much water the dependant that depends on water could die or too little dependant can die (dependant=plants)
Explanation:
Answer: 125 g
Explanation:
To calculate the moles :
The balanced reaction is:
According to stoichiometry :
1 mole of 
require = 3 moles of 
Thus 1.30 moles of will require=
of
Mass of 
Thus 125 g of will be needed to burn 36.1 g of
Answer:
The unknown substance is Au ( gold)
Explanation:
SiO2 has a high melting point, is insoluble in water but is a very poor conductor. So the statements do not apply here.
F2 is soluble in water, has a melting point way lower than 1064 °C, and isa gas. F2 doesn't apply here.
Au is insoluble in water, has a high melting point, is a good conductor and is hard. Gold applies are all those statements.
Kbr is good soluble in water, and is a bad conductorbecause it is just a powder, and the molecules have no mobility, and therefore it cannot conduct electricity. The unknown substance is not Kbr.
The unknown substance is Au ( gold)
