If your tween is like most, coming home to an empty house probably feels very bad to her. Most youngsters spend their home-alone time feeling lost; many are lonely and some are frankly frightened. Small difficulties can escalate into crises if your child panics or makes a poor decision.
A tween may believe she should be grown up enough not to need someone to look after her. She may put on quite a display of bravado, but that doesn't mean she necessarily feels secure staying by herself. Many tweens lack the maturity to handle time alone. They haven't been sufficiently involved in the daily operations of the household to know how to exercise good judgment when problems arise.
If you are uneasy about leaving your child alone but can't take her with you, make arrangements for her to spend the time at a friend's or a relative's house. Otherwise, hire a sitter. However, your tween may feel awkward about having a baby-sitter. Employing a boy sitter for a boy and a girl sitter for a girl may help.
If you must leave your child home for extended periods, call to check on her frequently and invite her to call as often as she needs to. Even if she doesn't call often, just knowing that she can is likely to be very reassuring.