Answer:
(a) 52.2 mL helium
(b) 18.0 g nitrogen
(c) 78.5 mg MSG
(d) 23,600,000 mm wavelength
(e) 0.00420 kg lead
Rounded the numbers to three nearest significant figures.
(2) CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)
(3) N2(g) + 3H2(g) → 2NH3(g)
(4) N2(g) + O2(g) → 2NO(g)
Answer:
4) N2(g) + O2(g) → 2NO(g)
Explanation:
In a chemical equation, the location of the word "heat" can be used to quickly determine whether the reaction is endothermic or exothermic. If heat is released as a product of the reaction, the reaction is exothermic. If heat is listed on the side of the reactants, the reaction is endothermic.
However in the options given, heat was not mentioned. this means we would have to undergo elimination process.
Option 2 represents combustion of methane, heat is a natural by product of any combustion reaction. hence, the correct answer cannot be 2.
Option 1 - The C=O bonds in CO2 have a high bond energy (the energy you would need to break them) which is more than either of the C-C or O=O bonds in the elements and their sum. Thus to create C and O2 from CO2 you would have to put in energy to break the two C=O bonds. You would get some back from the C-C and O=O bonds but less. Thus you need to add a lot of energy to convert CO2 into its elements. (You can decompose it at high temperatures.)
The reverse process gives off heat. So again, the correct answer cannot be 1.
Option 3 - The heat of formation of H2 ( g ) and N2( gas) under the standard condition is zero ( 0), and heat of formation of NH3 ( g ) is -46.11 kj / mol, so for the formation of 2 moles of NH3( g ) it would be - 92.22 kj,
The -ve symbol is indicative of the above reaction is exothermic in nature. So again, the correct answer cannot be 3.
Our only option left is 4 - The standard enthalpy of formation of nitric oxide (NO) in the gas phase is about +90 kJ/mol, which is endothermic. The primary reason for this is that the nitrogen-nitrogen triple bond is very strong (941 kJ/mol). The energy cost to break that bond as well as the oxygen-oxygen double bond (495 kJ/mol) is not compensated by the forming of the nitrogen-oxygen double bond (607 kJ/mol). Endothermic reactions are the result of breaking strong bonds and forming weaker ones.
Answer:analysis
Explanation:
Answer
Explanation:
Acid and base have different characteristic which identify either it is acid or base.
1. Substance A is tested and found to have a pH of 3.
This option is for acid because acid have pH in the range of 0-6
2. Substance B, a common food, tastes sour?
This option is also for acid because acid have sour taste.
3. Substance C causes metals to corrode.
This option is also for acid because acid can cause corrosion
4. Substance D feels slippery in solution
This option is not for acid but it is for base because bases have the properties of slippery.
its atomic weight
its atomic formula
its atomic structure
Answer: Option (b) is the correct answer.
Explanation:
Atomic weight is also known as atomic mass or molar mass of an atom.
Atomic mass means the sum of total number of protons and neutrons present in an atom.
For example, atomic mass of HCl is atomic mass of hydrogen + atomic mass of chlorine.
That is, atomic mass of HCl is 1.01 g/mol + 35.453 g/mol = 36.463 g/mol
Thus, we can conclude that molar mass of any element is always equal to its atomic weight.