Shelley has a balloon with a small amount of baking soda in it. She fits the open end of the balloon over a graduated cylinder containing some vinegar. As she lifts the end of the balloon, the baking soda pours into the vinegar causing bubbling and fizzing to occur. Marie observes the balloon begin to "fill" up. Based on these observations, which of these can Marie determine about the new substance formed by mixing baking soda with vinegar?