Từ các dữ kiện sau: C (than chì) + O2(k) → CO2(k) H1 = -393,5kJ
H2(k) + 1/2O2(k) → H2O (l) H2 = -285,8kJ
2C2H6(k) + 7O2(k) → 4CO2(k) + 6H2O(l) H3 = -3119,6kJ
Tính biến thiên entanpi chuẩn của phản ứng ở cùng điều kiện:
2C(than chì) + 3H2(k) → C2H6(k) H4 = ?

In numbering carbon atoms in the parent chain of a hydrocarbon, why would you number from right to left, rather than left to right

In pqr m< p=60 m< q= 30 and m

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.