$("#projectIDSelect").html("Please select a Project ID").addClass("error-msg"); // chained methods

<p>
    <label for="projectIDSelect">Project ID<span class="required">*</span></label>

    <!--Place to load the Project Names into for selection -->
    <select class="col-lg-3 col-md-3 col-sm-4 col-xs-6"  style="height:30px; color:black;" id="projectIDSelect" name="projectIDSelect" required>
        <option value="" disabled selected>Select a Project</option>
    </select>
</p>