Option 1/A (It is the first one)
HCl = H⁺ + Cl⁻
c(HCl)=9.8*10⁻⁵ mol/l
pH=-lg[H⁺]
[H⁺]=c(HCl)
pH=-lg{c(HCl)}
pH=-lg{9.8*10⁻⁵}=4.009
pH=4.009
ANSWER: boiling water
Explanation: the others are physical changes
Answer:
Blank 1: 1
Blank 2: 2
Blank 3: 1
Blank 4: 1
Explanation:
Assuming this is to balance the equation, write out the amount of each element you have on the reactants side and on the products side
Reactants Products
Ca 1 Ca 1
C 2 C 2
H 2 H 4
O 1 O 2
Comparing the two, we can see that hydrogen and oxygen have different amounts between reactants and products. Therefore, we need to multiply by some number to get the two equal. If we multiply the reactants by 2 we will get the correct amount in the products. So we put a 2 in front of the H₂O to signify this.
The balanced chemical reaction is
CaC₂ + 2 H₂O --> C₂H₂ + Ca(OH)₂
