24St. = strong
Q1 St acid among follwing in non polar acetic acid medium is ?
a)HF
b)H2SO4
c)HClO4
d)HI
Q2 Write ionic eqn for
NaH +H2O→ ?
Q3 Why there is very litle diff in acid strength of H3PO2,H3PO3,H3PO4 ??
Q4 T/F
i)carbonates of Na,K,NH4+ are soluble in water
ii)Carbonates of Ca,Ba,Sr are soluble in water
Q5 SiO2 +HF (moist)→
Q6 SiO2 +Caustic soda(aq)(hot)→
-
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17 Answers
1Q.5) Both the equations given are right. both result in silicic acid only. i hv reacted one step more of the reaction given by tushar.
24and also whats significance of word "moist" ???
does reaction occur differently with anhydrous condition ?
24and why there are 2 diff ans for Q5 ???
btw is this ionic eqn ok naa??
NaH --->Na+ + H-
H- +H2O --->OH- +H2
24here are options for Q3
a)P is not highly EN atom
b)the hydrogen atom in these acids is not directly bonded to P atom
c)phosphorous exists in diff oxidn states in these acids
d)all of above
11Ans 5) Silica (Si O2) in any form is unreactive. It is an acidic oxide, and so does not reacts with acids. However it does reacts with HF, forming silicon tetraflouride Si F4. This reacn is used in qualitative analysis to detect silicates.
H2SO4 + CaF2 → HF + SiO2 → SiF4 + H2O→ HF + { Si(OH)4 or SiO2. 2H2O}
Ans 6) SiO2 + NaOH → (Na2 SiO3) n and Na4 SiO4
1Q.3) Though the basicity decreases from H3PO4 to H3PO2 , but the little difference in acidic strength cn be becoz of their high reducing character.
Actually , among the three hydrogens , if any no. of 'H' ' s is basic , then the remaining ones are reducing. thus, the reducing 'H' 's if released during reduction reaction cn be treated as basic.
Q.5) HF + SiO2 → [ SiF6 ]2- (flouro silicic acid) + H2O
This reaction is called etching of glass.
Q.6) SiO2 + NaOH → (Na2 SiO3)n and Na4 SiO4
1@debo ,r u sure of wht u hv said abt Q.4 (ii).
becoz , solubility of carbonates in gr - 2 metals decreases down the group. so, first two carbonates i.e. Be and Mg are soluble while others are not. still , the answer is false.
Q.1 ) Here , 'St.' is strongest or stable ?
11hhmm ok (it's ionic so my 2nd ans is wrong) eure.......... but what abt the other's ????
24@ debo thats why this ques is here[3]....ans given is diff[6]
@ttush..ionic eqn for Q2
i have this long eqn....
19ans 1 > a ...due to hydrogen bonding in HF with acetic acid !
ans 4> (i) -F(amm carbonate is insoluble)
(ii) -F(only alkali metal carbonates are soluble)