Answer:
The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance (the decimal associated with percent of atoms of that element that are of a given isotopе). An element does not have an absolute atomic mass.
<em>Hope</em><em> this</em><em> </em><em>helps</em><em> </em><em>:</em><em>)</em>
Double replacement means a reaction that includes two molecules that each have two different ions. After the reaction, the ions pairs have switched, which is what is shown in the above equation.
A single replacement would be a very simple reactions such as:
2Fe(II)S + Ov2^2- -> 2Fe(II)O + 2S^2-
A decomposition reaction would be shown as this:
2NaCl -(dissolve in water)> 2Na^+ + Clv2^-
A synthesis reaction could be the exact opposite:
2Na^1+ + Clv2^1- -> 2NaCl
<u>We are given:</u>
Initial Temperature = 90°c
Final Temperature = 120°c
Heat applied(ΔH) = 500 Joules
Specific heat(c) = 0.9 Joules / g°C
Mass of Aluminium(m) = ?
<u>Change in temperature:</u>
ΔT = Final temp. - Inital Temp.
ΔT = 120 - 90
ΔT = 30°c
<u>Calculating the mass:</u>
We know the formula:
ΔH = mcΔT
replacing the values:
500 = m(0.9)(30)
500 = m(27)
m = 500/27
m = 18.52 grams
Answer:
3 significant digits
Explanation:
The first 0 don't count (that's the rule in significant digits). So 3,0,0 are left over. Count them and total will be 3 significant digits. (remember the last zero count if there is a decimal but the first zeros doesn't count even with the decimals)
