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QUESTION;
Understanding the enthalpy definition=
Measurements show that the enthalpy of a mixture of gaseous reactants increases by 125.kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that -71.kJ of work is done on the mixture during the reaction. Calculate the change in enthalpy of the gas mixture during the reaction and determine if the reaction is endothermic or exothermic.
ANSWER: The change in enthalpy of the gas mixture during the reaction is 54.kJ
The reaction is endothermic.
EXPLANATION: Enthalpy is the heat change in a system.
To calculate enthalpy we use the formula below;
H = E + PV
H is the enthalpy
E is the energy used in the reaction
PV is the product of pressure and volume which is refered to as the work done in the system
Using the equation above
H = 125 + (-71) = 54.kJ
An endothermic reaction is a type of reaction where heat is gained by the system from it's environment, and the enthalpy of such system is positive. While an Exothermic reaction is a type of reaction where heat is lost by the system to it's environment, and the enthalpy of such system is negative.
Because our enthalpy value is positive, this is an endothermic reaction.
Answer:
In the case of water, an object with a density less than 1 g/cm3 will float. The closer its density is to 1 g/cm3, the more of it will sit below the water level.
Explanation:
Whether an object will float or sink is dependent on its density, and on the density of the liquid it is placed in.
Hey there: !
density = 19.32 g/cm³
mass = 54.82 g
Volume = ?
therefore:
D = m / V
19.32 = 54.82 / V
V = 54.82 / 19.32
V = 2.837 cm³
It should be 40.08 grams...because the atomic mass is equivalent to 1 mole of atoms of an element in grams, and 6.023 × 10^23 atoms of calcium is the same as 1 mole of calcium.
Hope this helps!