math
how many positive integers less than or equal to 100 have a prime factor that is greater than 4?
Social studies
Which century did the industrial revolution start?
chemistry
a 10.0L ballon contains helium gas at a pressure of 655mmHg, what is the new pressure, in mmHg, of the helium gas at 20.0L, if no change in temp or amount of gas
Chemistry
If PV=nRT, (100)(2x10^-5)=(n)x(8.31)x(300), n is 8.02x10^-7. How did you manage to get the mr of 42?
Chemistry
0.0337g of a volatile liquid when vaporized completely at 100Pa and 300K occupied a volume of 20cm3. When this volume of vapor was completely burnt in an excess of oxygen, 40cm3 of carbon dioxide and 20cm3 of water vapor were formed. All volumes being measured at the same temp...
chemistry
calculate the energy, in joules and calories required to heat 25.0g of water form 12.5 deg. celcius to 25.7 deg. celcius i know the answer just need to see how to do it especially the calories
Angermanagement
You could have hurt a loved one in many different ways: - not being honest - loss of trust - cheating on your partner - abusive tendencies; yelling, physical contact - letting them down Think to a time when your loved one had been angry or sad with your about something. What d...
Chemistry
Upon recalculating this you are definitely correct...log(1.6667)=0.22 so 7.2+.22=7.42 and the pH is then 7.42 Thanks again for your help.
Chemistry
Okay, so based on the chart in my book I was able to determine the following. pH=(unknown) pKa=7.2 of Phosphoric Acid (2) A-=.5M of Na2HPO4 HA=.3M H2PO4- pH= 7.2 + log(.5/.3) pH=7.2+log(1.6667) pH=7.2+0.5108 So, the pH of this solution is: pH=7.7108 Correct?
Chemistry
If a liter of a buffer is prepared with a final concentration of .3M monosodium phosphate and .5M disodium phosphate, what is the pH of this buffer? (Hint: Which is conjugate acid (HA) and conjugate base (A-)? What's the pKa for this particular pair of HA and A-?) So I thi...
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