Answer:
8.9 KJ
Explanation:
Given data:
Mass of strip = 251 g
Initial temperature = 22.8 °C
Final temperature = 75.9 °C
Specific heat capacity of granite = 0.67 j/g.°C
Solution:
Specific heat capacity:
It is the amount of heat required to raise the temperature of one gram of substance by one degree.
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = 75.9 °C - 22.8 °C
ΔT = 53.1 °C
Q = 251 g × 0.67 j/g.°C × 53.1 °C
Q = 8929.8 J
Jolue to KJ.
8929.8J ×1 KJ / 1000 J
8.9 KJ
M(NiS₂) = 11.2 g.
n(NiS₂) = m(NiS₂) ÷ M(NiS₂).
n(NiS₂) = 11.2 g ÷ 122.8 g/mol.
n(NiS₂) = 0.091 mol.
m(O₂) = 5.43 g.
n(O₂) = 5.43 g ÷ 32 g/mol.
n(O₂) = 0.17 mol; limiting reactant.
From chemical reaction: n(NiS₂) : n(O₂) = 2 : 5.
0.091 mol : n(O₂) = 2 : 5.
n(O₂) = 0.2275 mol, not enough.
n(NiO) = 4.89 g .
n(O₂) : n(NiS) = 5 : 2.
n(NiS) = 0.068 mol.
m(NiS) = 0.068 mol · 74.7 g/mol = 5.08 g.
percent yield = 4.89 g / 5.08 g · 100% = 96.2%.
Explanation:
Given elements:
F, Sr, P, Ca, O, Br, Rb, Sb, Li, S
Elements with the same chemical reactivity will belong to the same group on the periodic table. This implies that elements in the same column will have the same reactivity;
Li and Rb are both alkali metals in group 1
Ca and Sr are both alkali earth metals in group 2
F and Br are halogens in group 7
O and S are group 6 elements
P and Sb are both in group 5 on the periodic table
So these groupings show elements with the same chemical properties.
Answer:
The density of O₂ gas is 1.71 
Explanation:
Density is a quantity that allows you to measure the amount of mass in a given volume of a substance. So density is defined as the quotient between the mass of a body and the volume it occupies:
An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of the gases:
P * V = n * R * T
So, you can get:
The relationship between number of moles and mass is:
Replacing:
So:
Knowing that 1 mol of O has 16 g, the molar mass of O₂ gas is 32 
.
Then:
In this case you know:
- P=1.27 atm
- molar mass of O₂= 32 .
- R= 0.0821
- T= 16 °C= 289 °K (0°C= 273°K)
Replacing:
Solving:
density= 1.71
<u><em>The density of O₂ gas is 1.71 </em></u><u><em></em></u>
Answer:
K will give up an electron more easily than Br.
Explanation:
Electronegativity of an element is a property that combines the ability of its atom to lose and gain electrons.
The lower the electronegativity value, the more electropositive an element is and the more readily it loses electrons.
From the data given, we see that Br has an E.N value of 3.0 and K has an E.N value of 0.82.
Therefore, Br is highly electronegative and it is able to attract electrons to itself whereas K has a low E.N value. K will give up electrons more readily.
Lookinf at other information in the table, the larger atomic radius and lower ionizaton energy of K are all pointers to how readily it would be able to lose electrons.
We can conclude that K is even a metal.
