Answer:
7430.5 Joules (7.4*10^4 Joules)
Explanation:
Q=mc∆T
where Q is energy in Joules.
Now m=250 g
c= 0.386 J/g°C
∆T = 99 - 22 = 77 °C
plugging the values in gives
Q=250*0.386*77=7430.5 Joules
(7.4*10^4 Joules, if 2 significant figures)
Answer:
5.8μg
Explanation:
According to the rate or decay law:
N/N₀ = exp(-λt)------------------------------- (1)
Where N = Current quantity, μg
N₀ = Original quantity, μg
λ= Decay constant day⁻¹
t = time in days
Since the half life is 4.5 days, we can calculate the λ from (1) by substituting N/N₀ = 0.5
0.5 = exp (-4.5λ)
ln 0.5 = -4.5λ
-0.6931 = -4.5λ
λ = -0.6931 /-4.5
=0.1540 day⁻¹
Substituting into (1) we have :
N/N₀ = exp(-0.154t)----------------------------- (2)
To receive 5.0 μg of the nuclide with a delivery time of 24 hours or 1 day:
N = 5.0 μg
N₀ = Unknown
t = 1 day
Substituting into (2) we have
[5/N₀] = exp (-0.154 x 1)
5/N₀ = 0.8572
N₀ = 5/0.8572
= 5.8329μg
≈ 5.8μg
The Chemist must order 5.8μg of 47-CaCO3
Answer:
the third one, measured or observed without changing the identity and composition of matter. because physical property does not under go any change but can be put back.
I believe it to be g/mol of Calcium carbonate
because to finde mass...u must have grams(g) as units....
it is the only one that have g as units
as for the first answer the avogadros number gives u the number of atoms in one mole of calcium carbonate....
the second one is based on ... At s.t.p one mole of gas occupies 22.4 dm³⇒to find volume
<span>A </span>chemical formula<span> is a way of expressing information about the proportions of </span>atoms<span> that constitute a particular</span>chemical compound<span>, using a single line of </span>chemical element<span> symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and </span>plus<span> (+) and </span>minus<span> (−) signs. A chemical formula is not a </span>chemical name showing how the atoms are arranged.
