Something moving. Change in temperature.
Answer:
120g
Explanation:
Step 1:
We'll begin by writing the balanced equation for the reaction.
Sn + 2HF —> SnF2 + H2
Step 2:
Determination of the number of mole HF needed to react with 3 moles of Sn.
From the balanced equation above,
1 mole of Sn and reacted with 2 moles of HF.
Therefore, 3 moles Sn will react with = 3 x 2 = 6 moles of HF.
Step 3:
Conversion of 6 moles of HF to grams.
Number of mole HF = 6 moles
Molar Mass of HF = 1 + 19 = 20g/mol
Mass of HF =..?
Mass = number of mole x molar Mass
Mass of HF = 6 x 20
Mass of HF = 120g
Therefore, 120g of HF is needed to react with 3 moles of Sn.
Using the ideal gas equation:
PV = nRT
Substituting n with mass / Mr
PV = mRT/Mr
Density = m/V
So rearranging:
Density = PMr/RT
P = 1 atm
R = 0.082 L atm / K mol
T = 273 K
Density = (1 x 80.6) / (0.082 x 273)
Density = 3.6 g / L
Answer:
Part A
The volume of the gaseous product is 
Part B
The volume of the the engine’s gaseous exhaust is 
Explanation:
Part A
From the question we are told that
The temperature is 
The pressure is 
The of 
The chemical equation for this combustion is
The number of moles of 
that reacted is mathematically represented as
The molar mass of is constant value which is
So 
The gaseous product in the reaction is 
and water vapour
Now from the reaction
2 moles of will react with 25 moles of 
to give (16 + 18) moles of and 
So
1 mole of will react with 12.5 moles of to give 17 moles of and
This implies that
0.8754 moles of will react with (12.5 * 0.8754 ) moles of to give (17 * 0.8754) of and
So the no of moles of gaseous product is
From the ideal gas law
making V the subject
Where R is the gas constant with a value 
Substituting values
Part B
From the reaction the number of moles of oxygen that reacted is
The volume is
No this volume is the 21% oxygen that reacted the 79% of air that did not react are the engine gaseous exhaust and this can be mathematically evaluated as
Substituting values
The effective nuclear charge is an innate property of a specific element. It is the pull of force that an electron feels from the nucleus. It is related to the valence electron by the equation: Z* = Z-S, where Z* is the effective nuclear charge, Z is the atomic number and S is the shielding constant.
For the following elements in the choices, these are their values of Z*:
Aluminum - +12.591
Beryllium - +1.912
Hydrogen - +1
Carbon - +4
The effective nuclear charge of Boron is +3. Thus, the answers are Aluminum and Carbon.
