Answer:
When a Magnesium Ribbon is burnt, a powdery substance called magnesium oxide is formed.
Explanation:
There has obviously been a chemical change because several chemical properties of the magnesium have been modified: the color, the texture and the mass.
The increase in mass is due to the fact that oxygen from the air has combined with the magnesium to make magnesium oxide, MgO.
The chemical equation, Mg + O2 MgO shows this reaction but it needs to be balanced to make 2Mg + O2 2MgO.
Using stoichiometry, we can convert this eqation into an equation with moles:
2 mol Mg + 1 mol O2 2 mol MgO.
Next, we convert to grams using atomic masses obtained from the periodic table:
48g Mg + 32g O2 80g MgO
Lastly, we determine the same thing in the proportions we used. In other words, we used only 0.15g of Mg (not 48g) so everything needs to be divided by 320. So 80 / 320 = 0.25 g. If we burn 0.15 g of Mg, we obtain 0.25 g of MgO.
Hope this helps!!!
This is my first answer.
0.2701 moles of water were evaporated from the sample by the heating process
Mass of evaporating dish = 8.365 g
mass of dish + hydrate = 18.597 g
mass of hydrate = (mass of dish + hydrate) - mass of dish
hydrate = 18.597 - 8.365 = 10.232 g
Mass of dehydrated material = (mass of dish + dehydrate ) - mass of dish
dehydrated material = 18.735 - 8.365 = 5.37 g
Mass of water evaporated = hydrate - dehydrate
mass of water = 10.232 - 5.37 = 4.862 g
Molar mass of water = 18 gm/mol
no. of moles of water evaporated = mass / molecular mass
moles = 4.862/18 = 0.2701 moles
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Answer:
A)provide a basis for virtually all modern anaesthetic techniques
restore tissue oxygen tension by improving oxygen availability in a wide range of conditions such as COPD, cyanosis, shock, severe hemorrhage, carbon monoxide poisoning, major trauma, cardiac/respiratory arrest
aid resuscitation
provide life support for artificially ventilated patients
aid cardiovascular stability
B)Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material (e.g. steel) in a room environment. ... Welding metal results when two pieces are heated to a temperature that produces a shared pool of molten metal.
The correct answer is C. It was based on the thoughts of an early philosopher.
Explanation:
An atom is a basic and smallest unit that composes matter and that determine the properties of elements. Regarding the development of ideas related to atoms these did not begin in science but in philosophy; indeed the first person that proposed matter or elements were composed of certain smaller units was the philosophers Leucippus and his pupil Democritus in Ancient Greece, who stated atoms were eternal, infinite and defined the qualities of an object, idea that was supported by other Greek philosophers. But it was not until 16th and 17th centuries after the Middle Ages that the term re-emerged and until the 19th century it was officially proposed and there were experiments by scientists that later became a theory. Therefore, the development of the earliest idea about attoms differs from later work of scientists is that the earliest idea was based on the thoughts of an early philosopher.
The answer is (2) 1.0 dm3. In a balanced equation, the ratio of the mole number of the compounds is equal to the coefficients. And the ratio of volume of gas is equal to the mole number under same condition. So the answer is 1.0 mol.
