1. Để xác định hàm lượng H3PO4 người ta hút 5ml dung dịch cần xác định, hòa tan định mức thành 250ml. Lấy 10ml sau khi định mức, đem chuẩn trực tiếpvới NaOH 0,086N chỉ thị phenolphtalein. Thể tích NaOH tiêu tốn cho quá trình chuẩn độ là 15,75ml. Viết các phản ứng xảy ra ? Tính hàm lượng g/lit H3PO4 ?

Sodium sulfate dissolves as follows: na2so4(s) → 2na+(aq) + so42- (aq). how many moles of na2so4 are required to make 1.0 l of solution in which the na concentration is 0.10 m?

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

Which theory was contradicted by experiments with the photoelectric effect? light spreads out after it passes through a small opening. as soon as light strikes metal, electrons will be ejected. visible light, regardless of color, will cause the ejection of electrons when striking metal. the kinetic energy of ejected electrons depends on the frequency of light that strikes the metal.