Chemistry, 01.09.2019 00:00 dsbdkbv2772

Why is a balanced equation necessary to solve any stoichiometry problem?

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Answer from: rasv4799

Basically; because a balanced equation will show how many molecules of one compound will react with how many molecules of another. This can be stated as the number of moles of one compound that will react with a given number of moles of another. You need to know the number of moles; so that you can translate the number of grams of one compound into moles; and then you can convert the number of moles of another into grams. eg: hydrogen combining with oxygen to produce water H2 + O2 = H2O Balanced equation: 2H2 + O2 = 2H2O Two moles of hydrogen react with one mole of oxygen If we have 8 grams of oxygen Molecular mass O2 = 32 (ie, 2x16) 8/32 = 1/4 mole O2 therefore, if 2 moles of hydrogen combine with one mole oxygen; 1/4x2 moles H2 combine with 1/4 mole O2 1/4X2 = 1/2 mole H2 Molecular mass H2 = 2.016 1/2 mole = 1.008g Therefore 1.008 g H2 reacts with 8 grams O2

Answer from: Quest

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

Answer from: Quest

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

Write 15 uses of a mercury barometer along with its characterestics

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