Options are provided in the given question, so the complete question is as follows:
Laboratory equipment is cleaned and properly stored after use primarily so that —
A. chemical products can be measured and recorded as data
B. time is saved in setting up the next experiment
C. toxic materials can be kept in the laboratory
D. the possibility of contamination in the laboratory is minimized
Answer:
D. the possibility of contamination in the laboratory is minimized
Explanation:
After the completion of experiments, all the laboratory equipment should be cleaned and properly stored to minimize the possibility of contamination in the laboratory.
Any contamination in the laboratory can affect the experiment and will not give an accurate result, so it is important to clean and store the equipment properly.
Hence, the correct answer is "D".
Dans 250 g de solution il y a 250×0,1 = 25g de chlorure de sodium.
Masse d'eau: 250g-25g = 225 g
masse volumique de l'eau 1 g cm-3 ; volume d'eau : 225 mL.
We can’t answer this question without any information. There is no explanation of the lab, nor is there any data.
Let's break this down. We know from our balanced equation that (in theory) we'll get the same number of moles of copper out of the reaction that we put into it. So we need to find the number of moles of CuSO4 we have in 200.0 grams. Using the molar mass of CuSO4:
200.0 grams CuSO4 * (1 mole CuSO4)/(159.61 grams CuSO4) =
1.253 moles CuSO4
We know that the moles of CuSO4 and Cu are one-to-one, so we should yield the same number of moles of copper. If we multiply by copper's molar mass, we get:
1.253 moles Cu * (63.55 grams Cu)/(1 mole Cu) = 79.63 grams Cu
