In balancing equations, we aim to get equal numbers of every type of atom on both sides of the equation, in order to satisfy the law of conservation of mass (which states that in a chemical reaction, every atom in the reactants is reorganised to form products, without exception). Therefore, let me walk you through question a:
<span>_Fe + _ H2SO4 --> _Fe2 (SO4)3 + _H2
First, take a stock-check of exactly what we currently have on each side (assuming that each _ represents a 1):
LHS: Fe = 1, H = 2, S = 1, O = 4
RHS: Fe = 2, H = 2, S = 3, O = 12,
There are two things to note here. Firstly, H2 (it should be subscript in reality) represents two hydrogen atoms bonded together as part of the ionic compound H2SO4 (sulphuric acid) - this two only applies to the symbol which is directly before it. Hence, H2SO4 only contains 1 sulphur atom, because the 2 applies to the hydrogen and the 4 applies to the oxygen. Secondly, the bracket before the 3 (which should also be subscript) means that there is 3 of everything within the bracket - (SO4)3 contains 3 sulphur atoms and 12 oxygen atoms (4 * 3 = 12).
Now let's start balancing. As a prerequisite, you must keep in mind that we can only add numbers in front of whole molecules, whereas it is not scientifically correct to change the little numbers (we could have two sulphuric acids instead of one, represented by 2H2SO4 (where the 2 would be a normal-sized 2 when written down), but we couldn't change H2SO4 to H3SO4).
The iron atoms can be balanced by having two iron atoms on the left-hand side instead of one:
2Fe </span>+ _ H2SO4 --> _Fe2 (SO4)3 + _H2
Now let's balance the sulphur atoms, by multiplying H2SO4 by 3:
2Fe + 3H2SO4 --> _Fe2 (SO4)3 + _H2
This has the added bonus of automatically balancing the oxygens too. This is because SO4- is an ion, which stays the same in a displacement reaction (which this one is). Take another stock check:
LHS: Fe = 2, H = 6, S = 3, O = 12
RHS: Fe = 2, H = 2, S = 3, O = 12
The only mismatch now is in the hydrogen atoms. This is simple to rectify because H2 appears on its own on the right-hand side. Just multiply H2 by 3 to finish off, and fill the third gap with a 1 because it has not been multiplied up. Alternatively, you can omit the 1 entirely:
2Fe + 3H2SO4 --> Fe2 (SO4)3 + 3H2
This is the balanced symbol equation for the displacement of hydrogen with iron in sulphuric acid.
For question b, I will just show you the stages without the explanation (I take the 3 before B2 to be a mistake, because it makes no sense to use 3B2Br6 when B2Br6 balances fine):
<span>B2 Br6 + _ HNO 3 -->_B(NO3)3 +_HBr
B2Br6 + _HNO3 --> _B(NO3)3 + 6HBr
B2Br6 + 6HNO3 --> _B(NO3)3 + 6HBr</span>
<span><span>B2Br6 + 6HNO3 --> 2B(NO3)3 + 6HBr</span>
Hopefully you can get the others now yourself. I hope this helped
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Use the volume and density of the gold statue to calculate the mass of the statue.
density = mass / volume, or rearranged, mass = density • volume
Convert the volume of the statue from L to mL so volume unit agrees with density unit
mass of statue = 19.3 g/mL • 1000 mL = 19 300 g
Mass of sand must be same as the mass of the statue, 19 300 g
Use the mass and density of the sand to calculate the volume of sand needed
density = mass / volume, or rearranged, volume = mass / density
volume of sand needed = 19 300 g / 23 g/mL = 8391 mL or 8.391 L
1b
Calculate the density of the statue from the measured mass and volume. If the calculated density agrees with the known density of gold, then the statue is made from pure gold.
density = mass / volume
Convert the mass from kg to g as you want the answer in g/mL so you can compare it to the reference value of gold given in the problem. 16.5 kg • 1000 g / 1 kg = 16 500 g
density of the statue = 16 500 g / 954 mL = 17.3 g/mL
Since this density, 17.3 g/mL is significantly different from the known density of gold, 19.3 g/mL, the statue cannot be made of pure gold. The gold was mixed with a less dense metal.
Answer:
A. 3.7 x 10⁻³
Explanation:
In the beginning of the reaction there are 0.200 moles of reactant. After 25 minutes, remain 0.108 moles. That means the moles that wer descomposed are:
0.200 moles - 0.108 moles = 0.092 moles of reactant were descomposed.
That descomposition occurs in 25 minutes. The average rate of descomposition in moles / minute are:
0.092 moles Methyl isonitrile / 25 minutes = 3.7x10⁻³ mol/min.
Right option is:
<h3>A. 3.7 x 10⁻³</h3>
Answer:
Saturated fat occurs naturally in red meat and dairy products. It's also found in baked goods and fried foods. Trans fat occurs naturally in small amounts in red meat and dairy products. Trans fat can also be manufactured by adding hydrogen to vegetable oil.
