hi uy_moo,
here I have installed zeal and its dependencies (libxkbcommon, qt5, qt5-webkit) and it seems to work fine.
does your qt5 package contain the file libqxcb.so?
Code:
$ grep libqxcb\.so /var/log/packages/qt5-5.6.1-*
usr/lib64/qt5/plugins/platforms/libqxcb.so
have you logged out and logged in again after having installed qt5?