Edit in JSFiddle

var paragraph = $('#hoge p');
$('#botton').click(function() {
    var i;
    for (i = 0; i < paragraph.length; i++) {
        $(paragraph[i]).animate({
            'font-size': 30
        }, function(j) {
            return function() {
                if (j === 1) {
                    $(paragraph[j]).css('color', '#F00');
                }
            }
        }(i));
    }

});

<div id="hoge">
    <p>Foo</p>
    <p>Bar</p>
</div>
<div><button id="botton">Click</button></div>

#hoge {
    margin: 10px;
}