Electrons group themselves in pairs in their energy levels. To calculate the number of electrons allowed in any energy level, find the square of the number representing the energy level and multiply it by two. Using this formula, atoms can have two electrons in their first energy level, eight in the second, and eighteen in their third. The quantity of electrons at each level grows as the number of the energy level increases.
10 grams of cocaine helps chalk to grow and the mass was increase a way lot more
We will get the molality from this formula:
Molality = no.of moles of solute / Kg of solvent
So first we need the no.of moles of KNO3 = the mass of KNO3 / molar mass of KNO3
no.of moles of KNO3 = 175 / 101.01 = 1.73 mol
By substitution in the molality formula:
∴ molality = 1.73 / (750/1000) = 2.3 Molal
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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.