All elements in their standard states (oxygen<span> gas, solid carbon in the form of graphite, etc.) have a standard </span>enthalpy of formation<span> of </span>zero<span>, as there is no change involved in their </span>formation<span>.</span>
Answer: -112200J
Explanation:
The amount of heat (Q) released from an heated substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)
Thus, Q = MCΦ
Since,
Q = ?
Mass of water vapour = 30.0g
C = 187 J/ G°C
Φ = (Final temperature - Initial temperature)
= 100°C - 120°C = -20°C
Then apply the formula, Q = MCΦ
Q = 30.0g x 187 J/ G°C x -20°C
Q = -112200J (The negative sign does indicates that heat was released to the surroundings)
Thus, -112200 joules of heat is released when cooling the superheated vapour.
Why does the chemical reaction seen here obey the law of conservation of matter?
<u><em>Answer:</em></u>
- Because there are the same number of atoms of each element shown on both sides
<u><em>Explanation</em></u>
- As in chemical reactions, atoms bonds are break and new bonds are formed. As new substance are formed but overall they have same elements, no new elements come from outside or go to outside. In other words , rearrangement of atoms take place but number of atoms remained same.
NaOH + HCl -----> NaCl + H2O
- As in above reaction there are the same number of atoms of each element shown on both sides .
Answer:
eight oxygen atoms
Explanation:
This formula shows that in one mole of this compound, there are 3 moles of Ca atoms that combine with 2 moles of the PO4(phosphate) groups, which gives a total of 2 moles of P atoms and 8 moles of 0 atoms.