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Questions in chemistry

📝 Answered - In decarboxylation of sodium butanoate at STP, 5600 mL of CO₂ gas is liberated. Calculate the moles of CO₂ liberated at STP.

📝 Answered - Using the information in the table, calculate the enthalpy of combustion of 1 mole of acetylene for the reaction: [tex]2 C_2 H_2 + 5 O_2 \rightarrow 4 CO_2 + 2 H_2 O[/tex] | Compound | [tex]\Delta H _{ f } (kJ/mol)[/tex] | | :------------------------- | :------------------------ | | methane ([tex]CH_4[/tex]) | -74.8 | | acetylene ([tex]C_2 H_2[/tex]) | 226.8 | | ethanol ([tex]C_2 H_6 O[/tex]) | -235.1 | | carbon dioxide ([tex]CO_2[/tex]) | -393.5 | | water ([tex]H_2 O[/tex]) | -241.8 |

📝 Answered - Which term describes a pure substance that is made up of only one type of atom? A. matter B. rock C. compound D. element

📝 Answered - The mass of 0.5 mole of nitrogen gas is: (1) greater than the mass of 0.5 mole of nitrogen atoms (2) less than the mass of 0.5 mole of nitrogen atoms (3) is equal to the mass of one mole of nitrogen atoms (4) is equal to the mass of 0.5 mole of nitrogen atoms

📝 Answered - Which reaction is endothermic? $HCl + NaOH \rightarrow NaCl + H _2 O +58 kJ$ $6 CO _2+12 H _2 O +$ energy $\rightarrow C _6 H _{12} O _6+6 O _2+6 H _2 O$ $2 Na + Cl _2 \rightarrow 2 NaCl +$ energy $2 C _2 H _6+7 O _2 \rightarrow 4 CO _2+6 H _2 O +2,502 kJ$

📝 Answered - 4. Compare LPG and wood as fuels. 5. Give reasons. (a) Water is not used to control fires involving electrical equipment. (b) LPG is a better domestic fuel than wood. (c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.

📝 Answered - Which is a pure substance? A. soda B. gasoline C. salt water D. carbon dioxide

📝 Answered - In an experiment, 1.288 g of copper oxide was obtained from 1.03 g of Cu. In another experiment, 3.672 g of copper oxide gave on reduction 2.938 g of copper. Which law of chemical combination can be illustrated by this example? (1) Law of conservation of mass (2) Law of constant proportion (3) Law of multiple proportion (4) None of these

📝 Answered - A compound with molar mass 159 was found to contain 39.62% Copper and 20.13% Sulfur. Suggest the molecular formula. Given atomic masses: Cu = 63, S = 32, and O = 16.

📝 Answered - Which are the products in the equation [tex]CH _3 SH +4 O _2 \rightarrow CO _2+ SO _2+2 H _2 O[/tex]? Check all that apply. [tex]CH _3 SH[/tex] [tex]O _2[/tex] [tex]CO _2[/tex] [tex]SO _2[/tex] [tex]H _2 O[/tex]