Answer:
972 ppm
Explanation:
Percent (parts per hundred - pph), parts per million & parts per billion are ratios of a component of interest divided by total mix of several components.
That is, given 28%, this says 28/100, or 28ppm says 28/10⁶, or 28ppb says 28/10⁹.
To convert from the given (=> any of the three concentration ratios) simply multiply (X) where you wish to go.
Examples:
- Convert 35% to ppm and ppb
- 35% = (35/100) x 10⁶ppm = 3.5 x 10⁵ ppm
- _______________________________
- Convert 43 ppm to %
- 43 ppm = (43/10⁶) x 100% = 4.3 x 10³%
- ______________________________
- Convert 81 ppb to ppm
- 81 ppb = (81/10⁹) x 10⁶ppm = 8.1 x 10⁻² ppm
Notice how each 'Given' is expressed as a ratio of amount/100 (given pph or %), or amount/10⁶ (given ppm) or amount/10⁹ (given ppb). All you need to do here is multiply by where you want to go.
=> Given % = (amount/100) x 10⁶ => ppm
=> Given ppm = (amount/10⁶) x 100 => %, or pph
=> Given ppb = (amount/10⁹) x 10⁶ => ppm
Given ratio x 100 = %, or x 10⁶ => ppm or x 10⁹ => ppb
Your Problem:
Given = (0.0972g/100g) x 10⁶ppm = 972 ppm
or, if you wish ppb => (0.0972g/100g) x 10⁹ppb = 972,000 ppb
Answer:
Heat change is -14,175 joules, Exothermic
Explanation:
We are given;
- Mass of aluminium bar as 350.0 g
- initial temperature as 70.0 °C
- Final temperature as 25 °C
We are required to determine the heat change and indicate whether endothermic or exothermic;
We know that;
Heat change = Mass of a substance × specific heat × change in temperature
In this case;
Mass of Aluminium = 350.0 g
Change in temperature = (25 - 70)
= -45° C
Specific heat of aluminium = 0.90 J/g°C
Therefore;
Heat change = 350.0 g × 0.90 J/g°C × -45°C
=-14,175 joules
The heat change is exothermic because it is a negative value, also because cooling process involves heat loss and thus an exothermic reaction.
Answer:
The plum-pudding model did not identify a central nucleus as the source of a positive charge.
Explanation:
Sir Joseph John Thomson, most popularly known as J J Thomson. He was a famous scientist who was awarded the Noble prize for Physics for his discovery of the subatomic particle, electron.
He placed his famous model of an atom which is known as plum pudding model. He proposed that the atoms are described as the negative particles that is floating within a soup of the diffuse positive charge.
But the main defect of his proposal was that it did not recognized the presence of a central nucleus as a positive charged source.
B is the answer. It just depends on the area you are in.
