0.10 M potassium chromate is slowly added to a solution containing 0.40 M AgNO3 and 0.40 M Ba(NO3)2. What is the Ag+ concentration when BaCrO4 just starts to precipitate? The K sp for Ag2CrO4 and BaCrO4 are 1.1 × 10-12 and 1.2××10-10 respectively

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

the ratio of the conjugate base to the acid required to attain the desired ph.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante