An an increase in
temperature lead to more effective collisions between reactant particles and an
increase in the rate of a chemical reaction because the number of
molecules with sufficient energy to react increases. The answer is number 3.
If the crucible wasn't covered with a lid the reactants may have produced a gas that was released into the surroundings, or mass may have been lost in the form of water vapour.
Answer:
Cupric ions
Explanation:
In the single displacement reaction shown, the cupric ions lost two electrons.
Cu²⁺ + 2e⁻ → Cu
The replacement of a metallic ion in solution by a metal atom higher in the activity series than than the metal in solution falls into this category of reactions.
Since Zn higher in the series, it displacements the cupric ions.
The question is incomplete, the complete question is;
Determine whether each melting point observation corresponds to a pure sample of a single compound or to an impure sample with multiple compounds.
Experimental melting point is BELOW literature value
Experimental melting point is CLOSE to literature value
WIDE melting point range
NARROW melting point range
Answer:
narrow melting point-pure sample of a single compound
experimental melting point is close to literature value-pure sample of a single compound
wide melting point range-impure sample of multiple compounds
experimental melting point is below literature value-impure sample of multiple compounds
Explanation:
The experimental melting point of a pure single compound is sharp and extremely close to the melting point of the substance as recorded in the literature. Usually, a pure substance melts within a narrow range of temperatures.
Impure samples of multiple compounds melt over a range of temperatures. Also if the experimental melting point is well below the record in literature, then the sample is contaminated by other compounds.
the answer is position no. 4
