Код:
.chatTitle::before {
    position: absolute;
    width:45px;
    height:45px; 
    top:12px;
    left:12px;
    content:'';
    background: url("Адрес Картинки") 0 0 no-repeat;
    background-size:40px;
    transition:all 0.3s ease;
}
.chatHeader:hover .chatTitle::before {
    -webkit-transform: scale(1.5);
    -ms-transform: scale(1.5);
    transform: scale(1.5);
}