Posts

Showing posts from March 2, 2019

Ubuntu Doesn’t start

Image
0 I have a PC with Windows 10. Yesterday I installed Ubuntu 16.04 in a second drive. When I was shutting down the computer from Ubuntu, it wouldn’t shut down but stuck with the message [number.number] reboot: System halted. So I tried what this video suggests: https://youtu.be/ZZBTSUbzT0g Unfortunately not only this didn’t work for me, but I can’t get into Ubuntu anymore. It is stuck in a purple screen. I heard though the sound Ubuntu makes to inform me to fill my password. boot grub2 windows-10 acpi share | improve this question edited Jan 19 at 1:50 karel 59.8k 13 129 151

Mixed mathematical chemical problem

Image
3 $begingroup$ How to calculate the concentration of all species present in a solution with $mathrm{0.3~M}$ $mathrm{NaH_2PO_4}$ ? The whole truth is that any time that you add any phosphate ion into an aqueous solution, then you will have all four phosphate species. The $mathrm{NaH_2PO_4}$ solution contains the ions $mathrm{Na^+}$ , $mathrm{H^+}$ , $mathrm{OH^−}$ , $mathrm{H_2PO_4^{-}}$ , $mathrm{HPO_4^{2-}}$ , $mathrm{PO_4^{3-}}$ and undissociated acid $mathrm{H_3PO_4}$ . I form seven independent equations in order to specify the unknown concentrations of the seven species present in an aqueous solution of $mathrm{NaH_2PO_4}$ . these equations are: $$ K_1 = frac{[mathrm{H^+}][mathrm{H_2PO_4^-}]}{[mathrm{H_3PO_4}]} = 7.6 times 10^{−3} tag{1}$$ $$K_2 = frac{[mathrm{H^+}][mathrm{HPO_4^{2-}}]}{[mathrm{