② Point B is the mass change of magnesium carbonate just after decomposition. If the mixture is 100g and the thermal weight loss rate is 22.7%, the decomposition weight loss of magnesium carbonate is 22.7g, which is the carbon dioxide generated by the decomposition of magnesium carbonate.
MgCO3△。 ? MgO+CO2↑，
84? Forty-four
m？ 22.7 grams
M = 43.3g
The mas fraction of magnesium carbonate is 43.3% or 0.433,
So the answer is: 43.3% or 0.433;
(2) Take 25.00 ml of test solution from the volumetric flask and adjust the pH value of the solution to about 9.5 with sodium hydroxide solution; Both magnesium ions and calcium ions react with the EDTA standard solution of c mol/L to consume V2mL EDTA solution. Then, take 25.00mL of test solution from the volumetric flask, adjust the pH to 1 1.2 ~ 12 with NaOH solution, and all magnesium ions are precipitated. Add 2 drops of K-B indicator, and continue to titrate with the EDTA standard solution of c mol/L to the end point. V2mL consumed by EDTA solution is the solution volume consumed by the reaction of calcium ions with EDTA standard solution with molar ratio of 1-V2. According to the data of two titrations, the reaction volume of magnesium ion with EDTA standard solution with molar ratio of 1: 1 Ca2+ was calculated.
So the answer is: adjust the pH to11.2 ~12 with NaOH solution;
① Mass fraction of magnesium carbonate in ①250ml solution =(V 1? V2)× 10？ 3l×cmol/l×84g/mol mg× 10× 100% = 84c(v 1？ V2)m%, so the answer is: 84c(V 1? V2)m %；
(2) According to the steps of preparing the solution, calculate and measure it with a measuring cylinder, dissolve it with a beaker and a glass rod, transfer the glass rod, clean it and transfer it to a 100ml volumetric flask, and finally use a rubber dropper to fix the volume to prepare the standard solution of 100mL c mol/L EDTA. The glass instruments needed are beaker, glass rod, measuring cylinder and 100mL volumetric flask.
So the answer is: 100mL volumetric flask, rubber-tipped dropper.