Answer:
7.96g, 33.79%
Explanation:
I'll try my best to explain the entire process behind this question ;)
From the question, you can write the reaction
Now, there are a few reasons it is like this. Oxygen is a diatomic element, meaning it doesn't and can't exist as just O. It exists as O₂. To balance, this, double the amount of water and hydrogen so there is an equal amount of each element on both sides of the reaction (4 H's, 2 O's on the reactant side, and 4 H's, 2 O's on the product side).
From this we can get a mole-to-mole ratio.
Onto the stoichiometry. Our goal in this is to convert from grams of water to grams of hydrogen, and we do so with a mole to mole ratio.
Basically, what I did was divide by water's molar mass to get moles of water, multiplied by the mole-to-mole ratio (2:2) to get moles of H2, and then multiplied by H2's molar mass to get what should be the amount of H2 produced by the reaction.
For percent yield, you can calculate it is such:
Plug the numbers in:
So, the percent yield is 33.79%
Answer: a for the first one , d for the second one, b for the third one.
Explanation:
Oceanic<span> crust tends to be denser and thinner than </span>continental<span> crust, so the denser</span>oceanic<span> crust gets bent and pulled under, or </span>subducted<span>, beneath the lighter and thicker </span>continental<span> crust. </span>
Taking into account the definition of calorimetry ans sensible heat, you need a heat of 38.72 kJ to raise the temperature of 400 g of ethanol from 20 °C to 60 °C.
<h3>What is calorimetry and sensible heat</h3>
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).
So, the equation that allows to calculate heat exchanges is:
Q = c× m× ΔT
where
- Q is the heat exchanged by a body of mass m.
- c is the specific heat substance c.
- ΔT is the temperature variation.
<h3>Amount of heat in this case</h3>
In this case, you know:
- Q= ?
- c= 2.42
- m= 400 g
- ΔT= Tfinal - Tinitial= 60 °C - 20 °C= 40 °C
Replacing in the definition of sensible hear:
Q = 2.42 × 400 g× 40 °C
Solving:
<u><em>Q= 38,720 J= 38.72 kJ</em></u>
Finally, you need a heat of 38.72 kJ to raise the temperature of 400 g of ethanol from 20 °C to 60 °C.
Learn more about sensible heat:
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Answer: The molecular formula will be 
Explanation:
Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.
Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.
To calculate the molecular formula, we need to find the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is:
empirical mass of 
Molecular mass= 214 g/mol
Thus molecular formula will be 
