It took 380,000 years for electrons to be trapped in orbits around nuclei, forming the first atoms.
These were mainly helium and hydrogen, which are still by far the most abundant elements in the universe. Present observations suggest that the first stars formed from clouds of gas around 150–200 million years after the Big Bang. Heavier atoms such as carbon, oxygen and iron, have since been continuously produced in the hearts of stars and catapulted throughout the universe in spectacular stellar explosions called supernovae.
Answer:
The nucleus has an overall positive charge as it contains the protons. Every atom has no overall charge (neutral). This is because they contain equal numbers of positive protons and negative electrons. These opposite charges cancel each other out making the atom neutral.
Explanation:
Answer:
The amount of heat required to raise the temperature of a 32g sample of water from 8°C to 22°C is 1,874.432 J
Explanation:
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
Sensible heat is the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).
Between heat and temperature there is a direct proportional relationship. The constant of proportionality depends on the substance that constitutes the body and its mass, and is the product of the specific heat and the mass of the body. So, the equation that allows to calculate heat exchanges is:
Q = c * m * ΔT
where Q is the heat exchanged by a body of mass m, constituted by a substance of specific heat c and where ΔT is the variation in temperature.
In this case:
- c= 4.184
- m= 32 g
- ΔT= Tfinal - Tinitial= 22°C - 8°C= 14°C
Replacing:
Q= 32 g* 4.184 *14 °C
Solving:
Q= 1,874.432 J
<u><em>The amount of heat required to raise the temperature of a 32g sample of water from 8°C to 22°C is 1,874.432 J</em></u>
Answer:
The pH of the solution is 9.43
Explanation:
sodium acetate = CH3COONa
after removing the spectator ion Na
CH3COO⁻ + H2O ⇄ CH3COOH + H3O⁺
since sodium acetate is a weak base, it will not react completely with water. Thus a value "x" will be used to make the products.
At equilibrium:
[CH3COO⁻] = 1.288 - x
[CH3COOH] = x
[H3O⁺] = x
Since a base is reacting with H2O, Kb is used at equilibrium: Kb=(1*10^-14)/(1.8*10^-5) = 5.6*10^-10)
Kb = [CH3COOH][H3O⁺]/[CH3COO⁻]
Kb = (x²)/(1.288-x) since the Kb is significantly lower than 1.288 we can make a mathematical assumption that x is significantly lower than 1.288.
5.6*10⁻¹⁰ = x²/1.288
x = [OH⁻] = 2.675*10⁻⁵ M
pOH = -log[OH⁻] = 4.57
pH=14-pOH = 14 - 4.57 = 9.43
The answer is <span>magnets.
Pseudoscience is a belief and not a scientific method. Diet, drugs, and exercise cannot be examples of pseudoscience since it is known they can improve the condition of arthritis. But, on the other side, magnets are not scientifically confirmed as useful in arthritis treatment. There is only a belief that magnets can cure arthritis. Therefore, magnets are the exaple of pseudoscience.</span>
