1) The elements making up the unknown substance almost always include carbon and hydrogen. Oxygen is often involved and nitrogen is involved sometimes. Other elements can be involved, but problems with C and H tend to predominate followed by C, H and O and then by C, H, O and N.
2) We must know the mass of the unknown substance before burning it.
3) All the carbon in the sample winds up as CO2 and all the hydrogen in the sample winds up as H2O.
4) If oxygen is part of the unknown compound, then its oxygen winds up incorporated into the oxides. The mass of oxygen in the sample will almost always be determined by subtraction.
5) Often the N is determined via a second experiment and this introduces a bit of complexity to the problem. Nitrogen dioxide is the usual product when nitrogen is involved. Sometimes the nitrogen product is N2, sometimes NH3.
6) Sometimes the problem asks you for the empirical formula and sometimes for the molecular formula (or both). Two points: (a) you have to know the molar mass to get to the molecular formula and (b) you have to calculate the empirical formla first, even if the question doesn't ask for it. A few lines below is a link that goes to a file that discusses how to go from empirical to molecular formulas.
Answer:
A) 2.27 grams of tungsten trioxide must be needed to prepare 1.80 g of tungsten.
B)To prepare 1.80 g of tungsten we will need 0.0587 grams of hydrogen gas.
Explanation:
A) Mass of tungsten prepared = 1.80 g
Moles of tungsten =
According to reaction, 1 mol of tungsten is obtained from 1 mole of tungsten trioxide.
Then 0.009783 moles of tungsten will be obtained from:
of tungsten trioxide
Mass of 0.009783 moles of tungsten trioxide :
0.009783 mol × 231.8 g/mol = 2.27 g
2.27 grams of tungsten trioxide must be needed to prepare 1.80 g of tungsten.
B) According to reaction,1 mol of tungsten is produced by 3 moles of hydrogen gas
Then 0.009783 moles of tungsten are produced by :
Mass of 0.02935 moles of hydrogen gas:
0.02935 mol × 2 g/mol =0.0587 g
To prepare 1.80 g of tungsten we will need 0.0587 grams of hydrogen gas.
False because there’s only 60% turbulence 20% heat 20% sound
<u>Answer:</u> The volume will decrease by a factor of 4.
<u>Explanation:</u>
To calculate the volume when temperature and pressure has changed, we use the equation given by combined gas law.
The equation follows:
where,
are the initial pressure, volume and temperature of the gas
are the final pressure, volume and temperature of the gas
We are given:
Putting values in above equation, we get:
Hence, the volume will decrease by a factor of 4.
Answer:
64
Explanation:
since it's a cube all sides are equal
and to calculate volume you multiply the length by the hieght by the width