It is c because there are many decades today.
This is an ideal gas law question. It uses the ideal gas law equation, PV =nRT.
P = pressure, V = volume, n = moles, R is the constant, and T is temperature in kelvin. The temperature needs to be converted Kevin first. To convert from Celsius to Kevin, you add 273, meaning that the temp in Kevin is 403K. Then plug all the info into the equation to solve for moles.
(1.00atm)(1.280L)=n(0.0821)(403K)
n = 0.0387moles
To find molar mass, divide mass by moles.
4.03g / 0.0387moles = 104.17g/mol
104g/mol rounded to three significant digits
Answer:
A barometer is an instrument used to measure air pressure and track weather systems. The most common unit of measurement used in barometers is the millibar (mb).
Explanation:
2Ca + O2 = 2CaO
First, determine which is the excess reactant
72.5 g Ca (1 mol) =1.8089725036
(40.078 g)
65 g O2 (1 mol) =2.0313769611
(15.999g × 2)
Since the ratio of to O2 is 2:1 in the balanced reaction, divide Ca's molar mass by 2 to get 0.9044862518. this isn't necessary because Ca is already obviously the limiting reactant. therefore, O2 is the excess reactant.
Now do the stoichiometry
72.5 g Ca (1 mol Ca) (1 mol O2)
(40.078 g Ca)(2 mol Ca)(31.998g O2)
=0.0282669621 g of O2 left over
