A second-order reaction starts with an initial concentration of 0.200 mol/L of the reactant. If the rate constant is 3.9 × 10–2 L/mol·s, what is the time required to decrease the initial concentration to 0.070 mol/L?

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

there is none because earth is stationary and flat.

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.

the answer is c.the valence of the atoms combine .