55.36 is the mass of Calcium Bromide is needed to make 0.500 L of 0.554 M solution.
Explanation:
Data given:
mass of Ca
= ?
molarity of the calcium bromide solution = 0.554 M
Volume of the calcium bromide solution= 0.5 L
First the moles of calcium bromide is calculated as:
molarity = 
number of moles = 0.554 x 0.5
number of moles = 0.277 moles of calcium bromide
atomic mass of calcium bromide = 199.89 grams/mole
mass = atomic mass x number of moles
mass of calcium bromide = 199.89 x 0.277
= 55.36 grams
mass of calcium bromide required is 55.36 grams to make solution of 0.554 M in a solution of 0.5 litres.
The answer is d. Since, carbon can form four covalent bonds it can react with other elements to create other organic compounds. The atomic number doesn't prove anything about organic compounds. The atomic number only says what is the charge of the element.
The given chemical reaction is:
The standard heats of formation of 
are:
Δ
) = -285.8kJ/mol[/tex]
Δ
) = -187.6 kJ/mol[/tex]
Calculating the change in heat:
Δ
=∑ΔH
-∑ΔH
= [{2 * (-285.8 kJ/mol)} -{2*(-187.6 kJ/mol)}]
= -196.4 kJ/mol
Therefore, the change in enthalpy for the given reaction is -196.4 kJ/mol
Carbs have larger molecules
Explanation:
The crucible is generally used in gravimetric analysis in which the unknown concentration is calculated by using mass.
The crucible is an important laboratory glassware which can bear high temperature in order to remove any impurities.
Crucible must be carried by a pair of tongs. If touched by hands, it will have impurities on its wall which will reflect in the readings.
Crucible is find difference between unfired sample ad fired sample. Any difference in the mass must be due to sample only, otherwise, results will be inaccurate.
When cold crucible is touched, it might pick up the moisture from the fingers if handled by the hand which making percent water to be reported high.
