Answer:
there are two significant figures is the number 8400
Explanation:
Answer:
The result is 3.859 in which we use four significant figures.
Explanation:
We start by solving the mathematical operation :
The result for the operation is 3.859438 but the numbers in the operation are given with four significant figures and that is why we are going to use four significant figures to express the result
To express 3.859438 with four significant figures we use the first four digits that appear from left to right starting by the first digit that is different to zero
In this case : 3.859 will be the result with four significant figures.
We also use a rule that says : To decide if the last significant figure remains the same we look for the value of the digit at its right.
If that number is greater than or equal to 5 ⇒ we sum one to the last significant figure
For example 3.859738 = 3.860 with four significant figures because the ''7'' is greater that 5
If that number is less than 5 ⇒ the last significant figure remains the same
In our case : 3.859438 = 3.859 because ''4'' is less than ''5''
Answer:
Hydrogen Chloride Gas is heavier than air and sinks to the ground after being released. Firefighters closer to the ground will be subjected to significantly greater concentrations of hydrogen chloride gas than the firefighters walking on top of railcars.
Explanation:
The molar mass of air is 28.97 g/mol. Air is approximately 78% N2, which has a molar mass of 28.014 g/mol and 21% oxygen, which has a molar mass of 32 g/mol; the remaining constituents of air include CO2 and other trace amounts of gases.
The molar mass of HCl is 36.458 g/mol.
Because HCl is heavier than air, it sinks toward the ground, displacing the lighter air.
The height of railway cars is reported to vary between 13.5 ft to 15.5 ft. So firefighters on tank cars are generally above the HCl gas (although localized atmospheric conditions could cause the HCl to move higher up in the air column).
10% is normally how it works .
For example like 1,000 is the top the next level would be 100 then the next would be 10
Answer:
The energy released as heat when 9.94 g Cu 2 O ( s ) undergo oxidation at constant pressure is -10.142 kJ
Explanation:
Here we have
2Cu₂O ( s ) + O₂ ( g ) ⟶ 4 CuO ( s ) Δ H ∘ rxn = − 292.0 kJ mol
In the above reaction, 2 Moles of Cu₂O (copper (I) oxide) react with one mole of O₂ to produce 4 moles of CuO, with the release of − 292.0 kJ/mol of energy
Therefore,
1 Moles of Cu₂O (copper (I) oxide) react with 0.5 mole of O₂ to produce 2 moles of CuO, with the release of − 146.0 kJ of energy
We have 9.94 g of Cu₂O with molar mass given as 143.09 g/mol
Hence the number of moles in 9.94 g of Cu₂O is given as
9.94/143.09 = 6.95 × 10⁻² moles of Cu₂O
6.95 × 10⁻² moles of Cu₂O will therefore produce 6.95 × 10⁻² × − 146.0 kJ mol or -10.142 kJ.
