# Search results

1. ### Chemistry review questions-calculations

Hi, I have some reviw questions for the upcomming chemistry exam, the problem is I don't have the answers so can some one read throught my work and check if it is wright? Thanks. *** 1. An anaysis of a valitile liquid shoed that it wsa composed of 14.4%C, 2.37% H and 83.49% Cl. If 4.25 g of...
2. ### Pleas help! exam tommarow Trigonometry word problems

Pleas help! exam tommarow!!!! Trigonometry word problems Hi, i really need help with this question, on a wall, a spider is 100cm above a fly. the fly starts moving horizontally at the speed of 10cm/s. After 1s, the spider begins moving at twice the speed of the fly, in such a way as to...
3. ### Sequence and series word problem

Tod injured his wrist while he was skateboarding. To relive the pain his doctor prescribed him some medication. He takes 500mg of medicine every 6h. Only 25 % of the medication remains in his body by the time he is ready to take another pill. Write and equation to model this. so 25% is...
4. ### Counting backwards; Sequences

Please help I have ALOT of questions!! 1.)Starting at 888 and counting backward by 7, a student counts 888, 881 and 874, and so on. Which of the following numbers will be included? a) 35 b) 34 c) 33 d) 32 e) 31 Ok, so I by using the calcuator the aswer is 34, but how would you calcuate...
5. ### Arithmetic series

OK, these questions are supposed to be really easy, but I keep geting the wrong answer and I don't understand why, could someone pleas look at my work and tell me what I am doing wrong? Find the indicated sum of each arithmetic series S15 for 4 + 11 + 18 + ... Sn= n/2 [ 2a + ( n - 1 ) d...
6. ### Iron ore extraction

I really don't know what catagoir this would go under :confused: , but its an assignment for chem so... Woud there be any positive envromental impacts of iron ore extraction? This was on of the topics we had to reaserch, but form 3 days of searching throught the net, positive effects iron ore...
7. ### Writing equations

Carbon monoxide reacts with the iron (lll) oxide. Would it be like this... 3Fe2 O3 + CO= 2Fe3 O4 + CO2
8. ### Neutralization calculations

A student obtains 25.00 mL of an HCl solution of unknown concentration. Upon titration, 21.35 mL of 0.1200 M NaOH are required for neutralization. Determine the concentration of the HCl solution. the capital M is molar mass right? but i thught that was constant so how can it be 0.1200 M NaOH...
9. ### Quick question-precipitate

when all the products are reatants are soluble there is no precipitate right?
10. ### Problem Solving question with circles

1.what is the equation of the largest circle that can be incribed in a square of side length 9 units, if the diagonals of the square intersect at (-1,3). where the radious is 9, but the ansewer in wrong *** 2.Todd is flying his radio-controilled airplane abouve the ground in a circular path...
11. ### Write an equation for the circle

Hi, I need help with these questions Given the endpoints of a diameter, write an equation for the circle. a) (-3,5) and (1,3) I tryed this m= (x1+x2)/2, (y1+y2)/2 = (-3+1)/2 , (5+3)/2 = -2/2, 8/2 = (-1,4) ( x-h)^2 + (y-k)^2=r^2 (x+1)^2 + (y-4)^2=r^2 (1+1)^2 +...
12. ### Pleas help! Chemistry calculations

the folowing reaction proceeds with a 70% yeild C6H6 + HNO3 = C6H5NO2 + H2O calculate the mass of C6H5NO2 expected if 12.8g of C6H5 reacts with excess HNO3 How do you do this problem?
13. ### Periodic function problem

I can someone pleas help me with this problem? Thanks. A periodic function f has a period of 12. If f(7)=-2 and f(11)=9, determine the value of f (43) how do you do this?
14. ### Trig functions translations and combinations of transfomations word problems

Hi, I really need help with this question 1) the water depth in a harber is 21m at hight tide, and 11m at low tide. One cycle is completed approximatly every 12h. a) find an equation for the water depth as a function of the time, t hours, after low tide b) Draw a graph 48h after low...
15. ### Calculations- molar concentrations PLS HELP

Hi, I need help with this question what is the molar concentration of 0.50 mol of NaCl dissolved in 0.30L of solution? =moles of solute/leters of solution =0.50mol/0.30L =1.7 mol/L Is this correct? and what mass of solute is present in 1.00L of 0.045 mol/L of Ca(oH)2, solution...
16. ### Does water have concentration

my answer would be yes because, a concentration is the measure of how much of a given substance there is mixed with another substance, so aslong as the water is mixed with something elce you can measure the concentation of water right?
17. ### Chemistry Molecular formula

what is the molecuar formula of CuSO4•xH2O? would it be CuSO4•5H2O?
18. ### Hydrated copper (II) sulfate mass calculation

calculate the precent by mass of water in a sample of hydrated copper (II) sulfate. mass of beaker-165.3g mass of beaker with bluestone-173.9g mass of dehydrated bluestone-170.7g Would this be a ballanced equation for this reaction? CuSO4•5H2O+ heat= CuSO4+5H2O so would you do this...
19. ### Chemistry Chemistry problems Moles

Hi, can some one pleas tell me how to do these questions? Thanks. How many atoms of C are in a mixture containing 0.237 mol of CO2 and 2.38 mol of CaC2? calclate the following the mass (g) of one atom of xenon the mass (g) of one mole of xenon atoms the number of atomic mass units in...
20. ### The ambigous case

I dont understand how to do these questions, involving angles less than 90 degrees. I know the "rules" you have to follow like if a<bsina there are two triangles etc. but what i dont understand is when there is a question, with no picture, how are you supposed to know witch one is the "a" and...