For which of the following activities might you want to hire a chemist?
Answer: D. testing a rock sample for gold content
Which of the following procedures involves a physical change in one of the substances?
Answer: C. separating a salt solution by evaporating the water
Answer is: 230 g.
Chemical reaction: P₄ + 5O₂ → 2P₂O₅.
m(P₄) = 100 g.
M(P₄) = 4 · 31 g/mol = 124 g/mol.
n(P₄) = m(P₄) ÷ M(P₄) = 100g ÷ 124g/mol = 0,806 mol.
From reaction: n(P₄) : n(P₂O5) = 1 : 2.
n(P₂O₅) = 1,612 mol.
m(P₂O₅) = 1,612 mol · 142g/mol = 230g.
M - molar mass.
n - amount of substance.
Answer:
The specific heat of the metal is 0.466 
Explanation:
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
The equation that allows calculating heat exchanges is:
Q = c * m * ΔT
where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.
In this case:
- Q= 2330 J
- c= ?
- m= 25 g
- ΔT= 200 °C
Replacing:
2330 J= c*25 g* 200 °C
Solving:
c=0.466
<u><em>The specific heat of the metal is 0.466 </em></u><u><em></em></u>
there are 6 moles of oxygen in Zn(No3)2
Answer:
a) 600 J
b) 75 W
Explanation:
Force= 400 N, distance = 150 cm = 1.5 m, time= 8s
a) Work is the product of force acting on an object and distance (or displacement). The S.I unit of work is the joules.
Work = force × distance = 400 × 1.5 = 600 J
b) Power is the amount of energy transferred per unit time. It is the ratio of work to time. The S.I unit of power is watt
Power = work/time = 600 / 8 = 75 W
