What volume of 0.205 MK2S solution is required to completely react with 185 mL of 0.120 MCo(NO3)2?

the balanced equation for the above reaction is as follows;

3NiCl₂ + 2K₃PO₄ ---> Ni₃(PO₄)₂ + 6KCl

stoichiometry of NiCl₂ to K₃PO₄ is 3:2

the number of NiCl₂ moles reacted - 0.0102 mol/L x 0.134 L = 0.00137 mol

according to molar ratio  

if 3 mol of NiCl₂ reacts with 2 mol of K₃PO₄

then 0.00137 mol of NiCl₂ reacts with - 2/3 x 0.00137 = 0.000911 mol of K₃PO₄

molarity of given K₃PO₄ solution - 0.205 M

there are 0.205 mol in 1000 mL  

therefore volume of 0.000911 mol - 0.000911 mol / 0.205 mol/L = 4.44 mL  

volume of K₃PO₄ needed is 4.44 mL

the answer is c i believe

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.