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Cleaning Slabs with Isopropyl Alcohol
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<p>[QUOTE="calcol, post: 6565384, member: 77639"]OK. Here’s the solution … pun, pun, pun. <img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie8" alt=":D" unselectable="on" unselectable="on" /></p><p><br /></p><p>V70 is the volume of 70% you want, and V90 is the amount of 90% needed to make V70. The mass of isopropanol is the same in either case. So:</p><p><br /></p><p>V70 x 70 = V90 x 90. Solving for V90: V90 = 0.778 x V70.</p><p><br /></p><p>If you have a certain amount of V90 and want to use it all to make V70, then the equation is: V70 = 1.29 x V90.</p><p><br /></p><p>Ideally, V90 should be put in a graduated cylinder and brought up to V70 with water. But it will be close enough to put V90 in a container and add a volume of water equal to V70-V90. The two methods are not completely identical because of partial specific volume, which I won’t go into.</p><p><br /></p><p>Say you want 1000 ml of 70%. Put 778 ml of V90 in a container and add 222 ml of water.</p><p><br /></p><p>Say you have 500 ml of 90% and want to use it all to make 70%. The V70 volume is 1.29 x 500 = 645 ml. Put the 500 ml of V90 in a container and add 145 ml of water.</p><p><br /></p><p>Cheap plastic graduated cylinders can be bought on eBay or from Amazon. The plastic in these cylinders (polypropylene) is not affected by isopropanol.</p><p><br /></p><p>Cal[/QUOTE]</p><p><br /></p>
[QUOTE="calcol, post: 6565384, member: 77639"]OK. Here’s the solution … pun, pun, pun. :D V70 is the volume of 70% you want, and V90 is the amount of 90% needed to make V70. The mass of isopropanol is the same in either case. So: V70 x 70 = V90 x 90. Solving for V90: V90 = 0.778 x V70. If you have a certain amount of V90 and want to use it all to make V70, then the equation is: V70 = 1.29 x V90. Ideally, V90 should be put in a graduated cylinder and brought up to V70 with water. But it will be close enough to put V90 in a container and add a volume of water equal to V70-V90. The two methods are not completely identical because of partial specific volume, which I won’t go into. Say you want 1000 ml of 70%. Put 778 ml of V90 in a container and add 222 ml of water. Say you have 500 ml of 90% and want to use it all to make 70%. The V70 volume is 1.29 x 500 = 645 ml. Put the 500 ml of V90 in a container and add 145 ml of water. Cheap plastic graduated cylinders can be bought on eBay or from Amazon. The plastic in these cylinders (polypropylene) is not affected by isopropanol. Cal[/QUOTE]
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