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A student is given a crucible and asked to prove whether it is made of pure platinum. She first weighs the crucible in air and then weighs it suspended in water (density $=0.9986 \mathrm{g} / \mathrm{mL}$ ). The readings are $860.2 \mathrm{g}$ and $820.2 \mathrm{g},$ respectively. Based on these measurements and given that the density of platinum is $21.45 \mathrm{g} / \mathrm{cm}^{3}$, what should her conclusion be? (Hint: An object suspended in a fluid is buoyed up by the mass of the fluid displaced by the object. Neglect the buoyance of air.)

Calculate the volume of crucible with and without water then compare using the equation.Since the volumes are almost the same then it is a platinum crucible.

Chemistry 101

Chapter 1

Chemistry: The Study of Change

Intro to Chemistry

Rice University

University of Maryland - University College

Brown University

Lectures

02:29

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry deals with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds. Chemistry also involves understanding the properties and interactions of individual atoms and molecules for use in larger-scale applications.

04:42

In chemistry and physics, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, "matter" generally includes atoms and anything made up of them, and any particles and objects that act as if they have both rest mass and volume. However it does not include massless particles such as photons, or other energy phenomena or waves such as light or sound. Matter exists in various states (known as phases) that are defined by various physical properties, such as state of matter, phase, shape, and density. The Standard Model of particle physics and the general theory of relativity describe fundamental particles and the fundamental forces acting between them that control the structure and dynamics of matter.

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mm. And this problem we're applying our communities principle. So this principle states the buoyant force on a solid object is equal to the weight of the water displaced. So it's useful for determining the volume and density of an object that's irregularly shaped because we can just submerge it in water and make indirect measurements in order to determine the density of the object. So we measure its mass in the air and it's effective mass with its submerged in water in order to do that. So we want to find the massive water displaced. And that would just be the massive metal in the air minus the mass of metal in the water. So from the problem, if we input these two values, we get the mass of the water displaced. What that means is when we put the object in the water, the volume of water goes up by a certain amount. And there's a certain mass of this water displaced by the metal. So we have the density of water and from the density of water. Using the mass of the water displaced, we can find the volume of water displaced. So we use equals um over B. And if we rearrange that we get B equals um divided by D. Somali. Music was a massive evidence. See? And then plugging in our values for water, we can find the volume of water displace. Then we can calculate the density of the object because the volume of the object can be equated to the volume of the water displaced by the object because of our communities principle. So DNC as you go through mass over volume of the metal object. And then we're just going to take the mass of the mental object that we got an air. So that would just be the mass of the object divided by volume of water displaced, which is also the volume of the object. And then from that we can get the density which we get 21.5. So we can see that the DNC of platinum that she I calculated Was 21.45. So we ended up getting 21.5 and we had to round 23 sig figs because we did addition and subtraction in this step. But you can see that it's basically the same value. So that means, yes, this is platinum.

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