May 2010 Chemistry

Test Preparation SAT Subject Test Preparation
81

<p>^2that’s what i thought. (@ communist)</p>

82

<p>How many can one usually miss on the raw score to get an 800? My chances are not looking too favorable. I guess I’ll retake in June.</p>

83

<p>and equal amount of a strong base and a weak acid results in a ph>7.</p>

84

<p>You can only miss one.</p>

85

<p>@ ilyssa1257</p>

<p>When you add strong base to the weak acid, it completely reacts because the strong base pulls off all of the hydrogen ions from acetic acid</p>

86

<p>@ilyssa
thats true…
shoot I donno if 100ml is true anymore</p>

87

<p>Question: There are 85 questions on the test but the raw score is out of 80.</p>

<p>Explain?</p>

88

<p>wait to get a 800 you can only miss one?
i thoughtyou can miss about 4</p>

89

<p>I was going by the Sparknotes rubric, but I’m confused as to how 85 questions translates to 80 raw.</p>

90

<p>@ilyssa/autumn</p>

<p>It was asking how much base you needed to neutralize the acid (dont over think). Neutralize=remove all acid. They react 1:1 ratio. </p>

<p>Look: [Weak</a> acid-strong base titration](<a href=“http://www.cartage.org.lb/en/themes/sciences/chemistry/Inorganicchemistry/AcidsBases/Acidsbasesindex/Weakacidstrong.htm]Weak”>http://www.cartage.org.lb/en/themes/sciences/chemistry/Inorganicchemistry/AcidsBases/Acidsbasesindex/Weakacidstrong.htm)</p>

91

<p>I have the PR rubric that is the same as the SparkNotes one, except there are 800’s for 81-85 also…</p>

92

<p>So it looks like you can miss 4 for an 800. The Sparknotes rubric is incomplete.</p>

93

<p>the one about the h2 and water displacement was tt, i think. because hydrogen is insoluble and can displace water, and it is less dense.</p>

94

<p>@communist
[Add</a> a Strong Base](<a href=“http://science.csustan.edu/tutorial/Phillips/Weak000mL.htm]Add”>http://science.csustan.edu/tutorial/Phillips/Weak000mL.htm)
they use HF and NaOH and when they add equal amounts the pH is 8?</p>

95

<p>@pokemon3</p>

<p>Lol that question was silly. you can’t get h2 from water displacement, only electrolysis (you know, run a current through). But the second part was true since it is less dense.</p>

96

<p>@ilyssa</p>

<p>The test didn’t ask about the pH. Only strong base and strong acid reactions make ph 7. It only asked how much was needed to remove the acid & base molecules (neutralize).</p>

97

<p>

Not true at all. We did this lab in my AP chem class. </p>

<p>

</p>

98

<p>@communist101, yeah you have to electrolyze the water for H2, but the only way you can measure it is if you submerge a buret in the water and let the hydrogen bubbles displace the water, allowing you to find its volume. It was TT.</p>

99

<p>H2 is insoluble and it is less dense so you can collect H2, it doesn’t ask you if the H2 is from the H2O.</p>

100

<p>@communist101, yeah you have to electrolyze the water for H2, but the only way you can measure it is if you submerge a buret in the water and let the hydrogen bubbles displace the water, allowing you to find its volume. It was TT.</p>

<p>i second this.</p>