The original material has decayed 75%
Further explanationGiven
two half-life
Required
The decayed sample
Solution
General formulas used in decay:
[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]
t = duration of decay
t 1/2 = half-life
N₀ = the number of initial radioactive atoms
Nt = the number of radioactive atoms left after decaying during T time
t = 2 x t 1/2
Input the value :
[tex]\tt \dfrac{Nt}{No}=\dfrac{1}{2}^2=\dfrac{1}{4}=25\%[/tex]
The amount of Nt = 25% No
Iron is a metal. The structure of iron is described as a lattice of positive ions in a sea of
electrons. Which of the following statements about iron are correct?
1 iron conducts electricity because the electrons are free to move
2 iron has a high melting point due to the strong covalent bonds
3 iron is an alloy
4 iron is malleable because the layers of atoms can slide over one another
A. 1 only
B. 1 and 3
C. 1 and 4
D. 2, 3 and 4
Answer: 1and 4
Explanation: iron is an element not an alloy. An ionic lattice is not bonded covalently.
Consider the following chemical equilibrium:
N2 (g) + 3H2 ⇌ 2NH3
Now write an equation below that shows how to calculate Kp from Kc for this reaction at an absolute temperature .
Answer:
Kp = Kc (RT) ^(-2)
Explanation:
For the reaction;
N2 (g) + 3H2 ⇄ 2NH3(g)
We can write;
Kc = [NH3]^2/[N2] [H2]^3
But
Kp = pNH3^2/pN2 . PH2^3
To convert from Kc to Kp
Kp = Kc (RT) ^Δn
where Δn is the change in number of moles going from reactants
to products.
For this reaction;
Δn = 2- (3+1) = -2
Kp = Kc (RT) ^(-2)
Heat will continue to move until the objects or areas have reached the same ______.
Answer: Thermal Equilibrium
Explanation:
Answer:
temperature
Explanation:
I think that's it i'm sorry if i'm wrong
what is a row of elements across the periodic table called
Answer:
a period
Explanation:
Answer: The row of elements across the periodic table is called "periods".
Explanation:
In the Periodic Table, there are seven rows of elements, which is called periods.
Given 450.98 g of Cu(NO3)2, how many moles of Ag can be made? Provide your final answer rounded to two decimal places.
Cu + 2 AgNO3 → Cu(NO3)2 + 2 Ag
Answer:
4.82 moles of Ag.
Explanation:
We'll begin by calculating the number of mole in 450.98 g of Cu(NO₃)₂. This can be obtained as follow:
Molar mass of Cu(NO₃)₂ = 63.5 + 2[14 + (16×3)]
= 63.5 + 2[14 + 48]
= 63.5 + 2[62]
= 63.5 + 124
= 187.5 g/mol
Mass of Cu(NO₃)₂ = 450.98 g
Mole of Cu(NO₃)₂ =?
Mole = mass /Molar mass
Mole of Cu(NO₃)₂ = 450.98 / 187.5
Mole of Cu(NO₃)₂ = 2.41 moles
Next, we shall determine the number of mole of Cu needed to produce 450.98 g (i.e 2.41 moles) of Cu(NO₃)₂. This can be obtained as follow:
Cu + 2AgNO₃ —> Cu(NO₃)₂ + 2Ag
From the balanced equation above,
1 mole of Cu reacted to produce 1 mole of Cu(NO₃)₂.
Therefore, 2.41 moles of Cu will also react to produce 2.41 moles of Cu(NO₃)₂.
Thus, 2.41 moles of Cu is needed for the reaction.
Finally, we shall determine the number of mole of Ag produced from the reaction. This can be obtained as follow:
From the balanced equation above,
1 mole of Cu reacted to produce 2 moles of Ag.
Therefore, 2.41 moles of Cu will react to produce = 2× 2.41 = 4.82 moles of Ag.
Thus, 4.82 moles of Ag were obtained from the reaction.