Final answer:
A reliable gravimetric analysis requires controlled conditions and a pure precipitate to ensure accurate mass measurements for calculating analyte concentration, while sample size, shape, and reagent storage temperature are less critical, provided they do not compromise the analysis.
Step-by-step explanation:
Gravimetric quantitative chemical analysis is a technique where the analytical process involves separating the analyte from a sample by physical or chemical processes and measuring the mass of the analyte, reaction product, and/or sample. For an analysis to be reliable, the conditions that must be met are tightly controlled, including the need for a pure precipitate that can be easily filtered out of the reaction mixture. This allows for accurate mass measurements which are used alongside stoichiometric relationships to calculate the concentration of the analyte.
The sample size and shape are not relevant as long as they do not interfere with the analysis. Additionally, all reagents do not necessarily have to be stored at room temperature; instead, each reagent should be stored under conditions that ensure its stability and purity.
Answering the student's question, the conditions that must be met for a gravimetric analysis to be reliable are controlled conditions and a pure precipitate. This ensures that the precipitate can be isolated, dried, and weighed accurately, which is critical for determining the analyte concentration.