Total # Posts: 27
Consider the reaction: 2 NaBH4(aq) + H2SO4(aq) → 2 H2(g) + Na2SO4(aq) + B2H6(g) What volume, in mL, of a 0.500 M solution of NaBH4 is required to produce 0.529 g of B2H6? H2SO4 is present in excess.
September 21, 2015
Katie had an unpaid balance of $1,734.50 on her credit card statement at the beginning of January. She made a payment of $165.00 during the month. If the interest rate on Katie's credit card was 7% per month on the unpaid balance, find the finance charge and the new ...
January 15, 2012
Four good friends, who love cats, have each named their cat after one of the other friends. Of the clues that follow, only one is true; the others are false. Which friend owns which cat? a.Candys cat is named either Dody or Alice. b.Betsys cat is named Alice. c....
November 10, 2011
HEENT: normal sulfanilic, normal hair distribution. Does this make sense, I can't understand the word after normal, it sounds like sulfanilic, but I can't determine if this makes sense
October 30, 2008
Please could someone remind me how to calculate mean speed? I have to work out the mean speed of lava flow that travelled 13.5km over 21 days. I don't expect the answer, but some help on how to obtain it would be heplful! Thank you. All you can do is average speed: Average...
May 7, 2007
Could anyone suggest the possible effect on the hydroshpere if there was a volcanic eruption? Many thanks it would be damged by the smoke from the volcanic eruption. Could you be more specific with your definition of 'damaged' please? What would happen to the water ...
May 2, 2007
Can anyone help me please? I have a sample of granite, which has been determined to have a U238-Pb date of 1120 Ma. How can I find out how this was determined? I have been trying to calculate this but my brain has frozen, so any help would be appreciated! I don't expect ...
April 30, 2007
I have to answer the question 'The age of granite can be determined using radiometric dating. Explain the basis for the determination of a 238 U-Pb radiometric date of 1120 Ma for granite'. Can anyone suggest any sources to help me? Thanks! http://www.jiskha.com/search...
April 27, 2007
Science - Geology
Could anyone suggest any good sources for examples of geological cross sections? I have to draw a cross section of igneous metamorphic and sedimentary rocks where the igneous cuts through the others and my head is not responding to this at all! Many thanks hi if you have a ...
April 24, 2007
Explain the meaning of the term 'regulating mortality factor' and how an understanding of this can lead to successful biological control of pests in agriculture and horticulture. Thanks!! If anyone truly understood it, there wouldn't be pests, would there? http://...
April 5, 2007
Identify 2 examples of the atoms or groups in the compound tocainide that could be involved in its binding to receptor sites in the body via hydrogen bonding. Give reasons for your conclusions. I have gathered that OH- and NH- bonds are an option, is this correct and if so why...
March 14, 2007
Please help! Complete equation by drawing structural formula(e) of the product(s). CH2=CH-CH-OH + CH3-CH-CH2-C =O CH3 CH3 -OH You will have to imagine the bonds as I can't draw vertical or diagonal lines! There are too many possibilities to imagine what you are trying to ...
March 13, 2007
In practice the methanol production process is operated at temps of 250-300c and at pressures of 50-100 atmospheres in the presence of a copper based catalyst. Are these operating conditions consistent with the aims of achieving a high equilibrium yield of methanol and a high ...
March 12, 2007
I have read Le Chateliers principle but am having a little trouble explaining the effect of pressure and temperature on the equilibrium yield of methanol (CH3OH). Can anyone also tell me the effect of the increase of temp will have on the rate of the reaction? Yield of ...
March 11, 2007
I have drawn Lewis structures for hydrogen cyanide and cyanogen. I need to state the noble gas (for each element) whose electron configuration is attained in the Lewis structures. Can anyone help as I am quite confused! Many thanks Previous posts have asked for the noble gas ...
March 4, 2007
Chemistry - Isotopes
The isotope caesium 137 has a half life of 30 years. How long will it take for the amount of this isotope in a sample of caesium to decay to one sixteenth of its original amount? Please can someone explain how I can calculate this from the quantities that have been stated? ...
February 28, 2007
Can anyone tell me why a hydrogen atom has so many spectral lines even though it has only one electron? Also how would I explain this using a diagram? There are many unfilled energy levels above ground. Excited electrons can move betwixt those levels on the way to ground. It ...
February 27, 2007
Please help! A drop of oil (volume 0.05 cm3) is released from a medicine dropper on to the calm surface of a pond where it spreads out to cover an area of 40 cm2. Assume that the oil film has a uniform thickness equal to the diameter of an oil molecule. Calculate the diameter ...
February 22, 2007