D The Part That Stays The Same
The combustion of methane, CH4, releases 890.4 kJ/mol. That is, when one mole of methane is burned, 890.4 kJ are given off to the surroundings. This means that the products have 890.4 kJ less than the reactants.
Answer:
7.65 moles of silver are produced
Explanation:
Zinc, Zn, reacts with silver nitrate, AgNO3, as follows:
Zn + 2AgNO3 → Zn(NO3)2 + 2Ag
<em>Where 1 mole of Zn reacts with an excess of AgNO3 to produce 2 moles of Ag</em>
To solve this question we must convert the mass of Zn to moles and, using the chemical equation, we can find the moles of Ag as follows:
<em>Moles Zn (Molar mass: 65.38g/mol):</em>
250g Zn * (1mol / 65.38g) = 3.824 moles Zn
<em>Moles Ag:</em>
3.824 moles Zn * (2mol Ag / 1mol Zn) =
<h3>7.65 moles of silver are produced</h3>
Answer: 1709.4 Joules
Explanation:
The quantity of Heat Energy (Q) released on cooling a heated substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)
Thus, Q = MCΦ
Since Q = ?
M = 18.5 grams
Recall that the specific heat capacity of copper C = 0.385 J/g.C
Φ = 285°C - 45°C = 240°C
Then, Q = MCΦ
Q = 18.5grams x 0.385 J/g.C x 240°C
Q = 1709.4 Joules
Thus, 1709.4 Joules is released when copper is cooled.
The average atomic mass of the imaginary element : 47.255 amu
<h3>Further explanation </h3>
The elements in nature have several types of isotopes
Isotopes are elements that have the same Atomic Number (Proton)
Atomic mass is the average atomic mass of all its isotopes
Mass atom X = mass isotope 1 . % + mass isotope 2.% ..
isotope E-47 47.011 amu, 87.34%
isotope E-48 48.008 amu, 6.895
isotope E-49 50.009 amu, 5.77%
The average atomic mass :
