how do i prevent separation anxiety from my dog?

i have a female 7 mon old chihuahua and she stays in her kennel for 6 hours because i have school and i get out at 2:00,and im with her for the rest of the day,then i let her out of her kennel and walk her but eveytime she sees a family memeber of mine she jumps up is that a sign and she is also chewing on things and scratching my carpet.what do i need to do there is no one to take care of her for six hours.and how do i make my chihuahua stop taking my potted plants outside she started to pull the plants out