They have same chemical properties
for example the elements of group VIII are called noble gases .They are unreactive, odorless and colorless.
Answer:
B. They are clones of the parent plant
Explanation:
The mass of CO2 produced by 26g of acetylene is 88g.
Given ,
In an oxyacetylene torch, acetylene gas (ethyne; HCCH) burns to produce carbon dioxide and water vapour.
The acetylene combustion reaction is given by,
H2O + HCCH + 5/2 O=O 2CO2
Heat of reaction for acetylene combustion = 1259kj/mol
CO2 has a molecular mass of 44g/mol.
2 moles of CO2 have a molecular mass of 88g.
On combustion, 1 mole of acetylene yields 2 moles of CO2.
Thus, 26g of acetylene produces 88g of CO2 when burned.
As a result, the mass of carbon dioxide produced by 26g of acetylene is 88g.
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Explanation:
what are you talking about tho
Answer:
- <u><em>It is positive when the bonds of the product store more energy than those of the reactants.</em></u>
Explanation:
The <em>standard enthalpy of formation</em>, <em>ΔHf</em>, is defined as the energy required to form 1 mole of a substance from its contituent elements under standard conditions of pressure and temperature.
Then, per defintion, when the elements are already at their standard states, there is not energy involved to form them from that very state; this is, the standard enthalpy of formation of the elements in their standard states is zero.
It is not zero for the compounds in its standard state, because energy should be released or absorbed to form the compounds from their consituent elements. Thus, the first choice is false.
When the bonds of the products store more energy than the those of the reactants, the difference is:
- ΔHf = ΔHf products - ΔHf reactants > 0, meaning that ΔHf is positive. Hence, the second statement is true.
Third is false because forming the compounds may require to use (absorb) or release (produce) energy, which means that ΔHf could be positive or negative.
Fourth statement is false, because the standard state of many elements is not liquid. For example, it is required to supply energy to iron to make it liquid. Thus, the enthalpy of formation of iron in liquid state is not zero.
