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what is that troubles u.. any part of this which u cant understand well one.can u explain question 14 in more detailed pls ?
Step 1
u have to first balance a equation for anhydrous nitrate which has a metal ion from group 2 .
X here is the metal from group 2 as this is anhydrous so no water vapor will be released (2XNO3)2(s) = 2XO(s) + 4N02(g )+O2(g) (where X is a metal from group 2). note that this nitrate equation applies for every group 2 metal nitrate that is anhydrous
Step 2.
u know that substance loses mass after reaction only if there is a product including a gas. in this case that is nitrate and oxygen.
step 3
question says that 5g of this nitrate loses 3.29g(this includes the total mass of both these gases) thus u come to conclude that 5g of that substance will give 1.71(5-3.29) as u know that the total mass of reactants and products is the same.
step 4
1g of nitrate will give (1.71/5)=0.342g of that oxide ok
step5
now make a equation
2X+2(16)/2X+4(14)+12(16)=0.342.
now plug in X calcium magnesium and the other two compounds in the equation and see which satisfies the equation.
if i put calcium 2(40)+2(16)/2(40)+4(14)+12(16) u will see it will equal to 0.342 which means calcium is the right option.
if u put magnesium 2(24)+2(16)/2(24)+4(14)+12(16) this will equal to 0.27 see