I believe Mendeleev formed his periodic table by atomic weight (nowadays we do it by atomic number) so he likely used those values.
Answer:
Explanation:
Calcium carbonate decomposes at high temperatures to give calcium oxide and carbon
dioxide as shown below.
CaCO3(s) = CaO(s) + CO2(g)
The Kp for this reaction is 1.16 at 800°C. A 5.00 L vessel containing 10.0 g of CaCO3(s)
was evacuated to remove the air, sealed, and then heated to 800°C. Ignoring the volume
occupied by the solid, what will overall mass percent of carbon in the solid once equilibrium is reached?
Answer:
benzamide
Explanation:
Compound melting Point ,ºC Melting Pont Mixture, ºC
X 131 - 133
trans-cinnamic 133 - 134 110 - 120
acid
benzamide 128 - 130 130-132
malic acid 131 -133 114 -124
Benzoin 135 - 137 108 - 116
The compound X is benzamide since the melting point range is the one closest to this compound ( 130-132 ºC)
The reason there is not an exact match is not due due to the presence of impurities. The presence of impurities always lower the melting point ( it is a coligative property such as the melting point depresion of salt and water )
The reason for the deviation must be be some other factors such as preparation of the sample in the capillary, errors in reading the thermometer, rate of heating, etc.